Are there any frame stampings or anything with the VIN or identification of the car on any first gens? I saw a '66 GTO frame this weekend that had, I believe, a Parish stamp, with "66" and at least a partial VIN of the car stamped on the side of the rear drivers frame rail. On the top surface of the rail, there were also numbers stamped in; didn't get a chance to see them real well though. If so, where is it? If not, how do you authenticate a frame and subframe?

F body sub frames did not have a VIN stamp. There are random numbers on them but they are likely tooling numbers and have nothing to do with the car the frame was assembled to. There are some detail differences between years; very early '67s did not have the large holes at the inner ends of the rails for shipment tie-down. Also all '67s have welded-on brackets to mount lower control arm bumpers. After asssembly a date code was stenciled on the frame but it wasn't meant to last and didn't.

There really isn't a sure-fire way to know if a frame is original to a car.