lcmc,
There is a long list of things to check to help validate if the car as an original X33 Z28, but the list is still not an absolute way to verify the car's origin. Having the original paperwork, original sales documentation, P.O.P, etc. is a big help. If the car still happens to have it original “DW” code tire pressure sticker #3961733 would be a positive sign. Obviously, if this is a numbers matching Z28, carefully document the VIN no. and date codes of the engine, transmission and rear axle date code.
If you have a copy of the 1969 Assembly Manual, study the RS option and where the vacuum hoses route thru the firewall, assuming the car has the RS option. Also, study in the manual where the Muncie 4-Speed speedometer cable enters the firewall vs. where the automatic trans speedo cable was routing, along with the cable retaining clips on the floor pan. These are two quick clues to check out that may help, but these two items can still be made to look original to the car, or carried over from a donor car.
There are many other clues to look for: a single 3/8” fuel line, multi-leaf rear springs, the reinforcement plate welded to the outside of the driver’s side rear frame for the duel exhaust hanger, just to mention a few.
I would also recommend that you buy the book, The Definitive 1969 Camaro Z28 – SS396 Fact Book, by Jerry MacNeish. It contains many good facts and pictures of original Z28 component that can be used as a guide. Also, CRG is a great site to study up on what was original on 1st Gen Z28.
Good luck with your decision.
