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.

1. External Features - 1966 Pontiac GTO

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

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 / Codes - 1966 Pontiac GTO

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 Top and Vinyl Top colors - 1966 Pontiac GTO

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

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.

  1. 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).
  2. 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.
  3. 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.
  4. 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).
  5. 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

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 Serial Number and Type Code - 1966 Pontiac GTO

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:

  1. Front of the block.
  2. Passenger side of the block.
  3. 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 Block Date and Casting Codes - 1966 Pontiac GTO

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 A B C D E F G H I J K L
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

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

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