http://www.thirdgen.org/techboard/tr...arts-list.html (Th400 parts list.)
Different tranny crossmember because the TH400 mount is much farther back.
An electric kickdown switch on the throttle somewhere.
A TH400 slip yoke. It has a larger diameter output shaft. You can't use a bolt on yoke found on most pickup trucks with a TH400.
A shorter driveshaft. Nothing is factory available so you need one custom made. Might as well switch over to 1350 u-joints while you're at it.
Some way to move the torque arm off the transmission and onto the tranny crossmember.
Buying an aftermarket torque arm with tranny crossmember solves a few of the problems. Buying a conversion swap kit solves a couple of others. You'll still need the TH400 slip yoke. New factory ones for 1350 u-joints are worth around $100
