INFO GUIDE: 1966 Pontiac GTO (Coupe, Hardtop & Convertible)

This identification guide has been drafted for the 1966 Pontiac GTO. For the 1967 Pontiac GTO guide, please click here. The 1966 GTO was the first to be offered as a distinct model, rather than an option package on the Pontiac ‘Tempest’, and featured new styling cues which further distinguished the car from others in the range. The result was particularly positive, with the 1966 GTO recording record sales.

Today, the 1966 model GTO is a particularly desirable muscle car, with all variants demanding high prices, but particularly so for high specification and original matching number cars. Although a 1966 model may not be difficult to identify on face value, this guide is focussed on providing people with information so they can assess the originality of a particular car, with respect to optional features, modifications, and of course the important ‘matching number’ elements.

This guide provides information on exterior features, interior features, mechanical features, paint colors/codes, as well as detailed chassis and engine number sections applicable to the 1966 Pontiac GTO.

Period of manufacture: September 1965 – November 1966

Number produced: Total: 96,946

Sports Coupe = 10,363
Convertible = 12,798
Hard Top (pillarless 2-door) = 73,785

Please note, this guide has been written based on a variety of online sources and enthusiast input. You should not rely on this guide to make any purchasing decision and we make no representation that all information is accurate. You should always seek independent professional advice when looking to purchase a unique car. If you have additional information, photographs or corrections you believe need to be made to this page, please contact us by clicking the button at the top of this page, or comment below.

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1. External Features - 1966 Pontiac GTO

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The 1966 Pontiac GTO had the following external features, distinguishing itself from the Tempest and Le Mans line as well as other GTO models. Where a feature is unique to the 1966 model, or shared with other models, this has been noted.

Available in three body styles:
- Hardtop (no B-pillar).
- Sports coupe (Coupe with B pillar).
- Convertible.
Fitted standard with steel 14 inch X 6 inch steel wheels for the entry level model. These were available painted several colors as outlined in the paints section of this guide).
Optionally fitted with the 14 inch X 6 inch ‘Rally I’ wheels. The wheels were painted ‘Rinshed-Mason’ Silver (Code E28C009), and were the same as the wheels used on the previous model year, however, the area around the wheel hub studs was black.
Wheels were fitted standard with Redline Firestone F70 x 14 tyres.
Front quarter rocker panel “GTO” badges noting the engine size (located at the rear of the front mudguard), held on by cadmium clips.
Aluminium front grille frame featuring a square patterned plastic black grille (the use of plastic was an industry first).
‘Louver’ style rear tail lights.
In contrast to later models, the 1966 GTO featured chrome work that followed the contours of the rear boot, and connected with the same contours moulded into the rear bumper.
“Pontiac” badge spelt out between the rear tail lights.
“GTO” badge featured on the left side of the front grille.
Front hood scoop.
Several additional aesthetic options were available for the 1966 model. See the options section of this guide for further details.
Non-factory ‘Hurst’ options were also available on the 1966 model, including unique mag wheels. Note, however, these were never an original equipment wheel for the 1966 GTO because they did not meet GM’s weight guidelines, but were nonetheless a popular add on. Hurst equipment was generally supplied with a badge, explaining those seen on many GTOs.

2. Interior Features - 1966 Pontiac GTO

1966 Pontiac GTO interior image Parchment seats 2.png

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The 1966 Pontiac GTO had the following interior features listed below. Many interior features may have been optional, and have therefore been outlined in section 10 of this guide.

“GTO” badge featured on the passenger side dashboard and on the door cards.
Timber veneer instrument cluster surround with four instrument dials (left to right): Fuel gauge/battery, speedo (120 MPH), tacho (5000 redline), water temp/oil pressure.
“LeMans Deluxe” steering wheel was fitted standard. A Custom sports steering wheel was an option. Both wheels had a Pontiac badge on the centre boss and are demonstrated in the images.
A white or black gear knob with the gear pattern in-laid on the knob was applied. A “Hurst” shifter mechanism and arm was also a period aftermarket item commonly applied to the 1966 GTO.
Various interior colors were available on the 1966 GTO, which have been summarised in the below table for the various sections of the interior.
The selected interior color will determine the color applied to the Dashboard, pillars, seats, roof lining and carpets (with the exception of Parchment, which featured Black carpets).
The above interior codes will be located on the vehicle data plate, in the engine bay (see images).
If the interior code has a “B” at the end of its sequence, this indicates bucket seats were installed. (e.g., “219-B”).
Where the data plate has a hole punched into it (see example in images), this means that the vehicle was factory equipped with a shoulder harness.

Interior vinyl trim codes (60° gloss) (seats, door cards):

Color Name	Data plate code	Du Pont Code	Ditzler Code	Rinshed Mason Code
Black	223	88	DL-9248	400-A-946
Medium Fawn (Gold)	221	9274-LH	DL-22571	66B84
Dark Blue	219	9268-LH	DL-13222	66B21
Dark Turquoise	220	9273-LH	DL-43533	66B31
Red	222	9183-LM	DL-71474	65B53R
Parchment*	224	9401L	22841	167B92

*Parchment interior came with black carpet

Upper instrument panel colors (0° gloss)

Color Name	Data plate code	Du Pont Code	Ditzler Code	Rinshed Mason Code
Charcoal / Gunmetal)	-	9191-LH	DIA-32466	65V13
Dark Blue	-	9284-LH	DIA-13216	66B27
Black	223	4428L	DIA9317	400-A-946
Dark Turquoise	220	9287-LH	DIA-43532	66B35
Red	222	9201-LM	DIA-71486	65B55M
Dark Fawn (Gold)	221	9198-LH	DIA-22533	65B87

3. Paint Colors - 1966 Pontiac GTO

1966 Pontiac GTO convertable Marina Turquoise 1.jpg

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The available paint colors for the 1966 Pontiac GTO are outlined in the table below. A sample of each of the paint colors has been given in the attached images. Note, the engine bay in all cars (firewall and inner guards) was always finished in ‘Chassis Black’ (no longer manufactured by GM). This is reportedly a close match for PPG (Specialty) ST1202 paint. A GTOs paint code is located on the vehicle’s data plate in the engine bay, as described in the attached images.

Body Paint:

Paint code	Paint Color Name	Lucite Code	Dulux Code	Rinshed Mason
A	Starlight Black	88L	93-005	A-946
B	Blue Charcoal	4622L	181-97211	A-1709
C	Cameo Ivory	4024L	93-93774	A-1199
D	Fontaine Blue	4630L	181-97219	A-1720
E	Nightwatch Blue	4631L	181-97220	A-1721
H	Palmetto Green	4633L	181-97223	A-1716
K	Reef Turquoise	4628L	181-97217	A-1718
L	Marina Turquoise	4703L	181-97561	A-1816
N	Burgundy	4624LH	181-97213M	A-1711M
P	Carrier Blue	4622L	181-97211	A-1822
R	Montero Red	4625LH	181-97540H	A-1712M
T	Martinique Bronze	4706L	181-97591	A-1821
V	Mission Beige	4401L	93-96261.	A-1530
W	Platinum	4708L	181-97593	A-1819
Y	Candlelight Cream	4709L	93-9794	A-1824

Wheel Paint:

Paint Color Name	Paint Code	Du Pont code	Ditzler Code	Rinshed Mason Code
Starlight Black	A	93-005	DQE-9300	P-403
Fontaine Blue	D	181-97219	DQE-13042	E-1720
Marina Turquoise	L	181-97561-H	DQE-43496	E-1816
Martinique Bronze	T	181-97591	DQE-22660	E-1821
Silver Textured (Rally I wheel only)	-	-	-	E28C009

Engine block paint:

Paint Color Name	Data plate code	Du Pont code	Ditzler Code	Rinshed Mason Code
Silver Blue		181-97219	13255	266T21

4. Convertible & Vinyl Tops - 1966 Pontiac GTO

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The 1966 GTO had three color options for the vinyl hard top, and five color options for the convertible top. The relevant codes for the original colors can be found on the vehicles data plate in the engine bay, next to but separated from the paint code with a hiphen. See the attached images for further details.

1966 GTO vinyl top colors and codes:

Color	Code
1	Ivory
2	Black
6	Beige

1966 GTO convertible top colors and codes:

Color	Code
White	1
Black	2
Blue	4
Turquoise	5
Beige	6

5. Chassis Number - 1966 Pontiac GTO

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The 1966 Pontiac GTO will have a 13 digit chassis number / VIN which can be decoded per the following table:

Character	Meaning	Correct Code for 1966 GTO
1	Manufacturer	2 = Pontiac
2 - 3	Series	42 = GTO
4 - 5	Body Style	17 = 2-dr Hardtop, 07 = Sports Coupe 67 = Convertible
6	Model Year	6 = 1966
7	Assembly Plant	A = Atlanta, B = Baltimore, C = SouthGate, E = Linden, G = Framingham, K = Kansas (Missouri), P = Pontiac, R = Arlington, U = Lordstown, V = Bloomfield, X = Kansas City (Kansas), Z = Fermont, 1 = Oshawa (Canada), 2 = Therese, (Canada).
8 - 13	Productoin Sequence #	6 digit unique production number.

Example: “242376B123456” = 1966 Pontiac GTO hard top built in Baltimore

Chassis number / VIN location:

The chassis number should appear in several locations on a 1966 GTO. These locations as described below, have been outlined in the attached images.

Embossed on the chassis plate, riveted to the front left door hinge panel with rosette rivets. (This is one long number which includes the chassis prefix and the unique vehicle production number as described above).
Embossed on the vehicle's data plate, riveted on the left side firewall/bulkhead, behind the brake booster. (Note, this plate contains only the first 5 digits of the chassis prefix, is preceded by the number "66", and a 3 digit ‘assembly plant’ code is applied. This plate does not contain the vehicle's unique production number matching that of the chassis plate.
Partial VIN may be stamped into various body panels of the car (such as on the firewall near the heater blower / AC hose, near the trunk lid seal, or on the driver’s side B-pillar). Pontiac did not stamp these areas in all production facilities.
The VIN should also be stamped into the engine block if the vehicle has its original engine (see engine number section of this guide for further details).
The VIN/ should also be stamped into the top of the vehicle's left rear chassis (frame), just behind the rear wheel where the frame goes over the axle. The body will need to be removed from the car to view this.

6. Data Plate Decoding - 1966 Pontiac GTO

1966 Pontiac GTO Data Plate fully decoded labelled.jpg

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The 1966 Pontiac GTO’s data plate provides a substantial amount of information about the car. The meanings of the various codes labelled in the attached images are outlined below.

Note, the 66 GTO has two possible data plate formats, which we have labelled “Data Plate Type 1” & “Data Plate Type 2” accordingly.

Code label	Meaning
Accessory Code	These codes confirm the options fitted in the factory. See section 10 of this ID-guide.
Assembly Plant	See attached chart showing assembly plant abbreviations.
Body Number	This is the production serial number of the body (believed to be for internal record purposes only), and is not to be confused with the chassis number.
Body Style	See section 2 of this guide for the body style codes and descriptions.
Paint / Vinyl / Ragtop Color	See section 4 of this guide for the relevant codes and colors.
Series	The vehicle series, such as Tempest, Lemans, GTO, etc.
Time Built Code	The number(s) represent the month in the year (e.g., 1 = January, 12 = December), and the letter represents the week of that month (e.g., A = Week 1, D = Week 4).
Trim Code	See section 2 of this guide for the various interior codes.
Year Model	Second two digits of the year of manufacture for the vehicle.
Harness Option	A hole punched where indicated confirms the vehicle was factory fitted with a shoulder seatbelt mounts.

7. Engine Number and Code - 1966 Pontiac GTO

1966 Pontiac GTO engine serial number and block code location.jpg

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Engine block serial number:

The 1966 GTO was fitted with a 389 CI Block, which should have a 6 digit serial number/VIN in three locations:

Front of the block.
Passenger side of the block.
Bottom of the block near the timing chain cover.

These locations are further described in the attached images. The block serial number should match the Chassis number found on the Chassis plate in order to qualify as a ‘matching numbers’ car.

Engine type code:

The engine code confirms the engine's specifications in terms of power, transmission, and carburettor system. This is a 2 letter code, located on the front of the engine block, below the right side cylinder head. The engine serial number is stamped above this engine block code. The table below outlines the various applicable codes and associated engine types:

Letter Code	Engine	Horsepower	Torque	Transmission
WS	8-389	360	424	Manual
WT	8-389	335	431	Manual
WW	8-389	335	431	Manual
WV	8-389	360	424	Manual
XE	8-389	335	431	Turbo Hydra-Matic
XS	8-389	360	424	Turbo Hydra-Matic
YR	8-389	360	424	Turbo Hydra-Matic
YS	8-389	335	431	Turbo Hydra-Matic

8. Engine Date & Casting - 1966 Pontiac GTO

1966 Pontiac GTO casting code date code on engine block.png

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Engine Date Code:

The date code consists of 3 or 4 characters. Character 1 = month, Character 2/3 = day, Last character = year. The date code is found at the back of the engine block just below cylinder 8, as shown in the images.

The following table outlines the month codes. Note, Code L refers to December 1965, as December 66 engines were being built for the 67 model GTO.

Code

Month

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

E.g. C146 = March 14 1966

Engine Casting Code:

The casting code is a code specific to the vehicle's year. The 1966 Pontiac GTO's 389Ci block should have the number 9778789 cast on the distributor Pad. See attached images for a better description of this location.

Engine Displacement Identification:

Unlike other V8 blocks produced by Pontiac during the 1960s, there are no 389 numbers cast anywhere on the block. Instead, to identify a 389 block, look for a notch on the passenger side deck where the block meets the head. See images for a better description of this identifier.

9. Mechanical Features - 1966 Pontiac GTO

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The 1966 Pontiac GTO had the following mechanical features:

The 1966 GTO was available with a 4 barrel Rochester carburettor, fitted to the 389CI block with varying power outputs from 335 to 360HP depending on the optioned engine configuration (see Engine codes section of this guide).
The 1966 GTO featured a revised Tri-Power carburettor (is Tri Power the brand?). You need to lookn into this more. I think Tri-Power was actually a reference to the cars having Triple Rochester carburetters?
A Ram Air 389CI engine was released putting out the highest power of 360HP. This had a redesigned camshaft and valve springs.
Aavailable in a 3 speed auto or 4 speed manual transmission.
Varying axle ratios were featured on the various gearbox and engine types per the below table. The differential ratio is stamped on the passenger side axle tube.
14” X 6” Rally 1 wheels were featured as an option on the 1966 GTO along with the standard 14” X 6” stamped steel wheels.
In the 1966 year model the GTO only came with 4 wheel 9.5 inch drum brakes. Disk brakes were not an available option.
Polished aluminium rocker covers

Differential Ratios:

Diff Code	Ratio
WB or YB	2.56
WC or YC	2.78
WD or YD	2.93
WE or YE	3.08
WF or YF	3.23
WG or YG	3.36
WH or YH	3.55
WK or YK	3.90
YL	4.33

10. Factory Options - 1966 Pontiac GTO

1966 Pontiac GTO optional wheel cover 1.png

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The 1966 Pontiac GTO was available with a large number of options, which we will endeavour to provide examples of. A full chart of options to be provided in this section shortly. In the meantime, please refer to the Collector's Originality Guide - Pontiac GTO 1964 - 1974, available through Google books.

11. References - 1966 Pontiac GTO

The following sources, among input from many enthusiasts, have contributed to the creation of this page. If you have any further information you believe can be added, please let us know by contacting us or commenting below.

www.classicregister.com

http://www.gtoforum.com

Pontiac GTO Restoration Guide (Book) by Paul Zazarine

https://en.wikipedia.org/wiki/Pontiac_GTO#1966

http://www.pontiacdiy.com

Collector’s Originality Guide Pontiac GTO 1964-1974 (Book)

www.hemmings.com

www.Classiccars.com

www.oldride.com

www.myclassicgarage.com

www.pontiachunters.com

Comments

sinned96

01/15/2020 - 13:22

The GTO option was never offered on the Tempest. It was only offered on the LeMans in 64 and 65 they both had a LeMans VIN number not a tempest to VIN number

Todd Depew

09/17/2018 - 10:16

Hi my name is Todd Depew. My father purchased Jim wangers 1966 Tiger gold GTO bobcat just days after he had turned it in at Royal Pontiac. It was stolen a year-and-a-half later from out in front of the house one night but recovered 4 weeks later.. They had taken the interior and drivetrain Plus all the VIN tags fast forward 52 years. Now we are looking to have it repainted but it seems there's no paint code for a tiger gold 66 GTO. Any help would be much appreciated.. Thank you.

postholeguy_3719

11/11/2018 - 04:44

Todd, if the GTO was painted Tiger Gold, the data plate on the firewall color code should be marked with 1- . This notates the GM limited production color. I own a 66 Thom McCan GTO that has this color on it from the factory. Please feel free to report back your findings on your I'D plate and I will get you the paint code from DuPont. This is a lacquer color. I was able to to do a spray out and convert it to base/clear with a color camera. Postholeguy@gmail.com

INFO GUIDE: 1966 Pontiac GTO (Coupe, Hardtop & Convertible)

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sinned96

Todd Depew

postholeguy_3719