[unruhjonny]

the model year was typically september of the prior calendar year through to august of the same (as model) year.

On occasion the “early” versus “late” has to do with a date which denoted a change in equipment.
Eg: Spring(?) 1973 emissions revision for 1973 model year vehicles

[Keith Seymore]

Production for the 1965 model year started on 8/24/1964 (in Pontiac Michigan, I assume).

K

[John V.]

Early is such a relative term. My ‘64 GTO was produced 11/20/63 at Fremont (for historical perspective, the Wednesday before JFK was shot).

I consider it relatively early because GTO sales hadn’t yet exploded, the bulk of the mag articles, especially the March Car and Driver article came later and a spike in GTO sales occurred in March and April from the records I’ve collected.

Sales of the ‘65 GTO were strong from the outset. Keith notes the start of production. In the first few days, line speed wasn’t yet cranked up as bugs were worked out.

Then there was the strike. The walkout occurred in late Sept (check the history books for the exact date) and production was halted. Production resumed after the strike was settled just before Election Day (LBJ wasn’t happy with the UAW as it was embarrassing to his presidency although the election results show it did little harm) and ramped up pretty quickly after that.

I believe the Pontiac Plant produced close to 300,000 cars for the ‘65 model year. Assuming yours was produced there, if the VIN was within maybe 5% of the total, that’s pretty early. Say lower than P115000 relative to the roughly 95% built at the Pontiac Plant after that. And assuming the percentage of GTOs remained fairly constant, you can guess that of the approximately 35,000 GTOs built at the Pontiac Plant (my rough estimate), roughly 33,250 were later builds.

But early isn’t especially meaningful except for situations as unruhjonny points out where a running change results in the need to distinguish between early and late builds.

One such early vs. late distinction for ‘65 IIRC was the change from the “rebuildable” fuel pump to the disposable type. I don’t recall if this affected the GTO.. I believe there was an alternator p/n change during ‘65 that has been discussed here in the past.