Hey Everybody, A long time lurker; however new to posting in the forum so here goes:
I have a 1989 full size Blazer, auto tranny. Wanting to swap out my dead 350K with a 400 small block that a friend is giving me for free. Will the 400 bolt right up? I want to keep the TBI so next question- Will 350 manifold with Throttle Body fit on the 400 engine? Don't want to get into extensive modifying to make this work.I appreciate the responses. Thanks.

 

I believe that everything should bolt up without issue.

The biggest concern that I would have is whether the ECU will be able to accept the changes and work properly with the new engine.

 

i think the flywheel MIGHT be different. i broke mine years ago and remembered i didnt use one off a 350 for whatever reason, so just use the one on the 400 if possible