1966 Chevelle SS396
Wish I could have found a build sheet for my 66, but it was built in Flint, and finding a build sheet in a Flint-built Chevelle is like winning the lottery.
Had two in my '70 Atlanta car, one tucked in the back of rear seat and a pristine one the back of the passenger door panel - still there, couldn't bear to remove it.Same here for me. Mine is a 69 Atlanta car. No build sheets in 69 Atlanta cars however oddly enough they are common in 70 Atlanta cars.
Did you look into the door jam at the hinge area / cowl, between the inner fender skirt and the outer fender, attached to the fender.Haven't found one in my 69 Elco, and there's only place left I haven't looked at yet - under the gas tank.
The tank still looks very much original, but I'm afraid I'd muck things up if I tried to take it out just to look.