I have a '66 suburban with the original 4spd. and the divorced Rockwell t-case. I can't decide if I shoud swap in a 700R4, 4L80E, or just add a Gear Vendors to my original drivetrain. The autos would be easier to drive, but the 4spd. granny low first is great off road and being able to split gears seems like it would make for a better tow rig. What do you guys think? Anyone have expierence with any of these trannys in older rigs? Thanks.