A 700R4, especially if it's a later one, post '86, will be just fine. There's thousands of them out there behind all sorts of engines. Also, the 700R4 was an option, and later std equipment in late model 'Burbs, which are much heavier than the ones from the '60s. They were also used in the lighter duty 3/4 ton pickups (my Dads '88 K2500 has one).

Bill Burmeister