Q: It’s been a while since I’ve looked at the ST* rules, but I thought you couldn’t update/backdate or do a package conversion. If that’s true, how do you pull off the Z28 stuff?

The rules are a bit tricky, but in Stock, you are allowed to do what’s called an “option package conversion”, within packages or models made the same year.  This is a lightweight version of the full “update/backdate” allowance of Street Prepared, that I cannot leverage.

What that means is, I can build a Z28 clone, so long as every part I am not “free” to change, is correct for the Z28.

Hypothetically speaking, let’s say there were two packages available on a car – the Base and the Sport.  The Base has a wimpy engine, a lightweight hood, and a small front sway bar.  The Sport has a better engine, a heavy hood, and a big front sway bar.  In Stock (and also Street Touring), you can convert your Base to a Sport, even if the codes in the VIN or on the option sticker are no longer correct.  The caveat is if you want the better engine of the Sport, you also have to run the heavy hood, because that was the only way you could get the better engine, and there are no allowances to change the hood.  You don’t have to change the front sway bar, because that part is “free” and you can run any front sway bar you like.

This allowance only works across cars built the same  year.  What this means is, I can convert my base ’67 coupe to ’67 Z28 specs, but I cannot convert it to ’68 or ’69 specs.  This limits some of my options as a lot of neat stuff became available later, especially in ’69.  Though of note, a lot of the parts of legend, like the dual-carb induction setups, were only ever offered as factory performance “trunk kits” (parts in trunk of car, not installed at factory), making them illegal for this class.

In the case of the ’67 Z28, it could only be had with a 302, M21 manual transmission, 12-bolt rear end, and power front disc brakes.  So at the very least, it’ll have all those things.  Back in the 60’s, manufacturers were much more flexible with options, so just about everything else you could get (or not), subject to some package-level restrictions.  The reason I chose a ’67 over ’68 or ’69 has to do specifically with the options available and mandated that year versus the later cars, which I’ll go into more detail over later.

It would have been cool to start with a ’67 Z28, but they only made 602 of them, it would have added a lot of cost without any real benefit for my purposes.