I've decided to go to the 400 turbohydramatic instead of rebuilding my 350 again. I know I'll need to change crossmembers, shorten my driveshaft, get a different trans. yoke, install a kickdown switch. Is there anything else I'll need? I'm looking at the TCI Super Street Fighter with manual/auto valve body. I'll be able to use my nearly new converter from the 350. (2600 stall) Thanks!

 

You sorta answered your own questions. That converter ought to slide right on. Only way to know for sure and not listen to me saying it will is to match the input shaft part numbers. If they use the same input shaft part for the 350 and 400, you are good to go.

 

I didn't have to shorten my driveshaft! Just had to replace the transmission end yoke with the 32 spline (bigger) to fit the turbo 400. Driveshaft shop method of checking driveshaft length: Slip trans yoke fully into trans output end until it stops and then pull it out one inch. Measure u-joint cup bores center to center for proper length info to give to shop. Mine needed no shortening which surprized me but saved a trip and $$$.