"Build Sheet."

I hope to soon start the restoration on my newly acquired 65 Barracuda. As best I can tell, the car is totally stock, un-touched. The only non-factory item in the car is a Radio Shack "Archer FM converter." I've seen several references to finding a "build sheet."
Where in the car (if there is one) would you might find one? The first thing I'm planning to do is gut the interior and if a build sheet is tucked away some where, I don't want to damage it.
Norm