the easiest tranny swap will be a G52 or G54 from any '84-87 carbed pickup. if you want to beef up a little, you can put a W56 in, but you'll have to change to a top shift t-case on most models('85-88 were top shift, '89-95 were forward shift but the rods are shorter so they won't work with a G tranny without a shift rod swap) and relocate the shifter holes.