[John V.]

In '64, Sales Code 612 was the Rally Handling Kit.

I have explained the change to this option between '64 and '65 many times on this forum. The gist is, in '64 you could NOT get the thicker 15/16" dia front stabilizer bar for a Tempest in combination with Power Steering except in a GTO.

The GTO package included the thicker bar so a GTO got it with or without PS.

The '64 612 Rally Handling Kit included the Q.R. manual steering box, the thicker bar, and the HD Springs and Shocks. The latter meant you got the 621 option as part of the 612 "package" and it was so noted on the Window Sticker.

The '64 621 would get you HD Springs and Shocks alone.

There were NO HD Springs available for the GTO, so the 621 in combination with the 612 or without the 612 only changed the Shocks. In non-GTOs, there were HD versions of the Springs that upgraded the standard release Springs.

The 612 was ordered as "Special Equipment", it was NOT listed on the regular Tempest Order Form.

For '65, PMD revamped the pieces. The thicker bar (still standard on the GTO) was now made part of the Sales Code 621 option rather than the "special equipment" 612 option.

By doing it this way, you could get the thicker bar with any Tempest, Tempest Custom, or non-GTO Lemans along with the PS option.

PMD did not call the 612 option "ride & handling" in '64.

A big takeaway here is that no matter that a '64 GTO Window Sticker would refer to the HD Springs & Shocks, you got the same Springs as any other '64 GTO. Only GTOs with AC got different front Springs, and with AC it also mattered whether or not it also had the optional auto trans. But the front Springs specified for the AC builds was PMD determined, you could not specify optional Springs for a GTO order.

When you ordered the 621 option for a GTO the ONLY thing that changed was the Shocks, this was true in '64 and '65.

And when you ordered the 612 option for a '64 GTO, the ONLY things that changed was the Q.R. steering box along with the Shocks. The Springs and front stabilizer bar remained the same.

The same was true in '65 but IIRC, PMD changed the description of the 621 option to "ride & handling" as it now included the thicker front bar. Meaningless to a GTO since it already included that bar but just a bit of PMD trivia to ponder.