I might be wrong and someone please correct me if I am. I think the LA cars were the only ones who put them on top of the gas tank. Norwood was best know for putting them under the rear seat. They have been found just about anywhere you could possibly put one. Behind the headliner,stuffed under the dash,in the front seat backs and under the console ect. There was no real system to where they were placed. Some cars even got build sheets from other cars. But dont get your hopes up on finding one in your car, Most did not get them. I just gutted the intire interior out of my 34,000 original mile unrestored 69 Z/28 and no luck.