[MylilBowTie]

4L80 I have no bones about = modern day th400, the 4L60 on the other hand is another story when it comes to power in a heavy vehicle that gets abuse of any kind.

If its safe to fab up a crossmember for the carrier bearing it be really easy to do it the right way. Transmission crossmember gets moved back toward the rear, cooler lines still work unless its a th475 is has bigger cooler ports, dipstick will work but you should use the one that comes with the th400 unless its not correct for it, kickdown switch isn't really that much of a concern right away it will still work fine without it, you will need to add a metal vacuum line for the th400s modulator valve from the rear of the intake to the modulator, convertor bolts up just the same, you will also want to get all your shift linkage parts off the 700r4 to use on the th400.

The main thing is the carrier bearing crossmember and driveshaft. In the case of getting a th400 with a 4in tailshaft. If you go with a th400 and two piece driveshaft the other thing you would want to pay attention to is if its a bolt on yoke or slip yoke. You will want a bolt on yoke.