First you either need a spacer and also the TH350/205 adapter, or replace the output shaft of the tranny with an Advanced Adapters shaft then use the TH350/205 adapter. I heard that the 205 behind the 700R4 without using the spacer will give you clearance problems with the front driveshaft hitting the tranny pan. You also would need to convert the 205 input to a 27 spline input. I am not sure if you can go backwards though from the 400 version to the 350 version, maybe someone else will chime in on that.