I'm unsure if you could figure it out from the VIN or not. I have to go to the dealer monday to order a few parts, and I'll see if they can tell by the VIN number.
Edit: Just remembered when I worked in the service dept. for Mr T, I could run the VIN and get a printout of all the options and equipment a car was sold with. Pretty much a copy of the window sticker. It may tell the original top color.
I have a tan top that is origional to the car. I bought the car 4 years ago from teh origional owner. Basically I assumed what the color of teh top was based upon what was there, there were a few tree sap stains. either or, lately I've been cleaning up the car more and more and ended up trying to clean off the tree sap stain, and shockingly, the top was changing color. Turns out the previous owner had it so dirty that the top was almost a completly different color. since I never saw another tan top up close, I didn't know
I guess this is somewhjat off topic, but I can't reco,mmend enough, use a top cleaner and clean your top, it really makes a difference where regular car wash soap failed.