There is actually not supposed to be any, policy was to dispose of them, but human nature is to do what is easier and faster (remember the workers were on a time limit to do the assigned task) If it was easier to stash the build sheet in a spot not seen by the customer was easier and faster than walking a few feet and tossing the sheet in the approved spot.
I have found a max of 3 in a 1979 Sunbird wagon parts car one under the carpeting, one under the back of the passenger seat back, and a 3rd behind the passenger side door panel with some markings that indicated rework of the window regulator on that door. Other common spots are above the gas tank, and headliner. But they can be located almost anywere they can't normally be seen by the owner.
78 Sunbird Safari Wagon, 3.8 N/A, 1971 Catalina Freeway Enforcer
77 Astre Formula, some day soon powered by a 215 Buick V-8
1973 4-speed Lemans Safari STOCK!!!!! 1978 Catalina Safari
1971 Lemans Safari/GTO Clone, 1969 Firebird Sprint 301 ci OHC6, T-5, 4.10 12 bolt posi