A Brief History of the (Gran Turismo Omologato) GTO.

  In 1963 an extraordinary thing happened. The GTO was born out of a dispute between Oldsmobile and Pontiac.   It seems that Oldsmobile had come up with the idea to put their 330 cubic-inch small block V-8 in their 1964 standard size, B-body Jetstar 88. Pontiac got wind of the idea and didn't like it because they viewed it as a threat to their Catalina. At that time it was believed that small engine-small car, big engine-big car. GM mandated that upper engine size for A-body was 330 cubic inches. Pontiac had in mind to put the 389 V-8 into the Tempest or Lemans A-body. This was stretching the limit, but not to be out done, they came up with a marketing idea.
  John Z. Delorean and Jim Wangers, who handled the advertising, decided to make the 389 V-8 an option on the Sporty Lemans. This happened midway through the year.
  By the time GM management found out what was happening the sales were beginning to soar. The idea and it's plan almost got axed. The original projection for sales was around 10,000. When 32,000 satisfied customers proved them wrong, GM management became convinced that there was something to this.
  Then other cars started to appear before the end of the year. Just a few were the 1964 Buick 4-4-2 and Skylark Gran Sport. Chevy came out with the 1965 Chevelle SS396.
  The Pontiac GTO known as "The Legend" and "The Great One," is the car that actually started the muscle car era. Pontiac production of the GTO from 1964 to 1974, was 514,793 GTOs being sold.

  Authenticating or identifying a GTO. 1964-1965 and 1972-1974 can be identified by the option (code on build sheet) on the Le Mans, while the 1966-1971 had their own (GTO model) designator in the VIN.

Example = (1964-1965) 824P100001, No GTO designator in the VIN.

Example = (1972-1974) 2D37T2P100001, No GTO designator in the VIN.

Example 1966-1971 (GTO model) = 242371P112045, 42 being the designator.