ford only used an automatic transmission behind a 460 until the 80s. i kno 460s were available in f350s in 73. i saw a camper special 140" wheelbase truck with one that was supposed to be all original. 79 was not the only year for a 460 in a f150. theres a 78 lariat f150 sitting in my back yard with a 460. and im 100% sure thats original