I have found three matching broad cast sheets in my first 70 Challenger T/A, I recently took apart a 70 Satellite convertible and found 4 broadcast sheets, One under the front seat was for a Purple 440 6 pac car the carpet was still original as well as the floor pan so I found a 70 Fy1 Yellow hardtop RR one there and then I pulled the rear seat and in the bottom one I found a 70 dark green 318 convertible one and then luckily I found a perfectly preserved one in the top half of the the rear seat. What I have seen is the there can potentially be 5 sheets per car from my past experience. I am not aware of an official number but maybe someone else will know. I have found them taped to the back of the glove box on E-bodies but have not found one there on b-body as of yet and the number of original cars are getting slimmer.

john