[Impala64ssa]

My baby was a 77F250 Camper Special W/460/C6/Dana 60, but I have owned several of that vintage.
My wife's uncle had a 69 F-250 that was very similar. He drove it all over the US and Canada. It had well over half a million miles on it when he sold it, but it still ran good.

[Norm Lenhart]

Probably the old FE 390. 600 pounds of power ;) The Chevys of that vintage were pretty beastly as well. Had a friend with a 68 stepside and an I6. Thing got like 18 mpg and refused to die. And it pulled like a mid sized V8.