Correct me if I'm wrong, but didn't all 69 Z's have vinyl tops? I'm probably wrong because I've seen a few without. But I was under the impression that that was a Z trademark from the Trans-Am circuit.

No not all.

Nope, most did not have vinyl tops. It was an option, like many things on the Z.Like -Power steering,tach,console,full gauges,cowl induction,spoilers(except late cars), among others.

The reason that some of the Trans Am cars (Penske) had vinyl roofs was because they acid dipped the bodies to lighten them up... they thinned the roofs out so much that at speed the roof skin would ripple and buckle... to disguise this they installed vinyl roofs.