About 1979, I became the owner of a 1971 Mach-1 -- or, more accurately, what was left of a 1971 Mach-1. The kid who first owned it went through 7 engines and 4 transmissions, and an assortment of driveshafts, and I know at least the gearing in the rear axle wasn't original. I don't have any elapsed time claims from anyone who knew that guy or the car when it was in the original owner's hands, but several people told me he was making "well over 500 horsepower" and that the car would do "between 125 and 130" in the (standing-start) 1/4-mile.
My parents sacrificed hugely for me: the shell