I know that the 700R4 for a V6 and V8 are differant on the out side but are the internal parts interchangable , I have the one for a V6 with a few problems and have had one from a V8 given to me that is almost completely new on the inside , but I need the one for the V6 fixed .

 

Some are, some aren't. Some of the drums for example hold different numbers of clutches.

That's on top of the 700's well-known lack of interchangeability among different versions of parts.

I'm no expert on such things; but I'd say, if you can't put the ENTIRE V8 trans into the 6-cyl case, you're asking for trouble. I wouldn't try to mix & match, as that virtually never works with that transmission.

 

Basically you would need to cahnge all internal parts, including the apply piston in the back of the case. Then all the V8 stuff should go right in. Just make sure you re-check/set the input shaft end play properly. Nothing is exact from one case to another, so re-check the back clutch pack hieght also.