The block code for the 1964 GTO consisted of a three-character (and sometimes four-character) code of numbers and letters. Beneath the block code is the unit number, which in this case is the same as the consecutive sequence number and is taken from the vehicle’s VIN. The block code is located on the passenger’s side of the engine block below the cylinder head/deck.
The date code is also important. It is cast in the distributor pad and consists of three or four characters as follows: The first is a letter representing the month (A for January, B for February, C for March, D for April, E for May, F for June, G for July, H for August, I for September, J for October, K for November, L for December, M for December 1966 [1967 model only]). The second or third is a digit representing the month. The last is a digit representing the year. N or D represents the work shift when the block was cast, Night or Day. (Beginning in 1969, an additional two numbers represent the year; for example, 69 for 1969.)
Engine Block Codes
Compression ratio is 10.75:1 on all engines.
Cylinder Head Casting Numbers
The cylinder head codes were cast into the center exhaust port area. For 1964, a portion of the head part number was also cast on the left- and right-end ports.
| Cylinder Head | Casting Number |
| 389 ci all | 9770716 |
Carburetors
The part number for the 1964 Carter AFB 4-barrel carburetor was found on a metal tag mounted on the carburetor air horn. For the Tri-Power carbs, the number was stamped on a plate and mounted on one of the carburetor mounting screws.
Distributors
The 1964 distributors had the part number stamped and mounted around the distributor shaft.
| Ignition | Part Number |
| Conventional | 1111054 |
| Transistor | 1111057 |
Intake Manifolds
On 4-barrel engines, the part number is stamped or cast into an intake runner. On Tri-Power manifolds, it can be found on the center and rear intake runners.
| Engine | Part Number |
| 4-barrel | 9770274 |
| 3×2-barrel | 9775088 |
Exhaust Manifolds
The part number for the exhaust manifold is generally, but not always, found on the outer face of the manifold.
| Location | Part Number |
| Driver’s side | 545467 |
| Passenger’s side | 9773442 |
On the Super Turbine 300 2-speed automatic, the transmission code was stamped on the low-servo cover on the passenger’s side of the transmission or on a metal tag.
The 3- and 4-speed M20 and M21 manual transmissions were used on the GTO and, generally, but not always, had the part number stenciled on the transmission case on the driver’s side of the case, at the rear of the cover. The code number indicated the type of transmission and the production date.
An identification code is marked in yellow paint on top of the case on 4-speed transmissions. W stands for wide-ratio and 9 stands for close-ratio. On the 3-speed Tempest (Muncie), the letter X indicates a heavy-duty Muncie and is marked on the passenger’s side of the case.
1964 Rear Axle Identification, Codes, and Ratios
In 1964, the axle ratio was stamped on the passenger-side axle tube and on the lower left side of the vent. Green paint was used on the top of the differential housing and on the hubs on GTOs made before January 2, 1964.
The M21 close-ratio 4-speed, according to the GTO club, was not installed by the factory.
The spacious interior provided plenty of room. The standard GTO steering wheel was the LeMans Deluxe wheel and optional was the Custom Sports steering wheel, which came with four brushed-metal spokes and an imitation wood rim. (Photo Courtesy Karl Lacker)
For an American car, the GTO had a European flair, but unlike the European cars, it was reasonably priced and could be loaded with lots of options. (Photo Courtesy Marty Cieslak)
The interior trim was identical to the LeMans. However, the GTO has the following items as standard and were not available on other LeMans models: the engine-turned appliqué that surrounds the fourgauge dash pods and the large GTO crest on the passenger’s side above the glove box.
All of these colors were available on the convertibles.
Exterior color codes can be found on the cowl data plate located on the driver’s side of the firewall and were consistent from plant to plant. The exterior color codes were found on the fifth line of the cowl data plate. The colors listed below were available on all models and were not just GTO colors.