I hear all these people saying that when you do a V6 to V8 swap you also have to change your tranny. What is the difference between a V6 and V8 700R4 tranny. I was talking to a guy at a booth at the Goodguys car show and he said there is no difference between these two transmissions. He told me that the 700R4 transmissions for the 4 bangers are the only ones that are different. They are called "baby 700R4's", but that V6 and V8 tansmissions are the same, with the same bolt patterns and everything. If the bolt patterns are the same on the V6 and V8 I don't see how it would be economical for GM to put different transmissions in V6 and V8 cars. Any help on this topic would be greatly appreciated.

bolt pattern

the 700R4 came behind 2 different chevy V6's

the 90* 4.3 (a 350 minus the #3&6 cylinders)
and the 60* 2.8 and 3.1

the 90* version of a 700R4 will have the same bolt pattern as a SBC

but the 60* version will not have the same bolt pattern, also because of the huge difference in size and shape, nobody offers an adapter plate

the only v6 that came in 3rd gen f-bodys was the 60*, so it is true that you will need a new transmission if swapping to a V8

also, i am not sure, but i believe the 4 cyl and 60* V6 700R4 are the same because they share the same bolt pattern...........if anybody would like to correct me on this, please do

The last post is correct. The 60° bolt pattern (aka "the baby 700R4) was used behind 4 cylinder engines, and 2.8/3.1 engines. The 90° bolt pattern is the 4.3 V6 and V8 engines.

Not only are the bolt patterns different, but the 60° transmissions used a 245mm Converter where as the 90° tranny used a 295mm converter. On top of that, each tranny had a different input shaft to accomodate the differenent torque converter.

If that wasn't enough, the 60° trannies usually had less clutches in the clutch packs as well.