Thanks to Bob Thibodeau for documenting the location of a C4's build sheets.
This photo shows the build sheet wedged between the front of the gas tank and
the body of the car.

These photos show the location of the front build sheet located inside the
chassis. The chassis openings are circled.
Armed with these pictures and a little luck I retrieved the build
sheet for my Vette.
It was impossible to remove the very fragile 20+ year old
sheet of paper from the chassis without ripping it.
However, a bunch of
small pieces of paper is better than no small pieces of paper. Once I had
extracted as many of the fragile little pieces of the build sheet as I could
from the car, I
laid all of the pieces together like a jig-saw puzzle and scanned the build
sheet:
The build sheet revealed where the car was originally purchased, its birth
date and a few
other factoids.