I'm looking to swap the tranny in my 1989 Chevy 3500 4x4 crew cab. It currently has a 350 from a 94 and the original 3 speed automatic what I believe to be a turbo 400. I'd like to put a 700r4 or a 4l80e with a "smart shift" unit in it for the electronics. I'm being told that I have to make adjustments to the front and rear drive lines as well as the bracket. Anyone already done this? Any help would be greatly appreciated. Thanks