I'll join in with the questionable memory thing, I put one of those 25 gallon C body tanks in an old Dodge pickup. I think I had to move the frame crossmember between the rear axle and the rear crossmember forward for that tank to fit. The moved crossmember was very close to the rear end. I also remember the fill tube (with a new gas cap) behind the plate would dump fuel if the tank was 3/4 or more full on hard acceleration, with the perspective of a 360 727, 3:23 gear drive train. That truck sat low, but the bottom of the tank was above the bottom of the rear bumper.