So, I have the 79 Bronc with my built 400 bolted to a C6 and np203 t-case. I love the 400 but I hate the C6 and the full time 4x4 203. Im looking at a donor 1978 bronco with a smogged down bone stock 351m but a solid 4speed manual and the np205 t-case. I really want my 400, and I really want the manual transmission and the part time t-case. plus it would be nice to have the stock 351 as a spare engine. Question is, can the bellhousing be changed so that i can stick either engine on either transmission? or can you only mate like-transmission engines? Ive never done a transmission swap like this before so sorry if this is obvious. I cant seem to get a clear answer on the rest of the forums either.

 

The 351m/400 are the same engines as far as exterior. Either one will bolt up to either tranny. I think you can even pull the flywheel off the 351m and bolt to the 400 and be a direct bolt in. It is possible the 400 uses a larger clutch/pressure plate but I am not sure.