I just need to know if the bell housing is the same on the 85-87 buick grand national, the 3.4 of the same 4th generation body, and the 3.8 of the 4th generation body are the same, if not, who sells adaptor plates?

 

Bolt pattern I'm sure is the same for the 3.4 and 3.8 (and therefore bellhousing) of the 4th Gen F-bodies, not sure about the older 3.8 blocks, but probably. Might check around in any Buick forums if you can for info on the older engine. (85-85 *might* still be BOP pattern, but then again, I think BOP is specifically for V8s). If it's not the GM v6 pattern, then it will likely be BOP.

 

Next question, in swapping over my harness, will the instruments on the dash still work? My coworker informed me that I'll be lucky to have a speedometer.