My 1966 dart race car.

recognized the solenoid and the support plate where the servo area is. The old ones didn't have that would would literally balloon the spacer plate in that area. Sounds like you've got a "top shelf" 904 now. If I were rainbow chasing I'd probably look into it.... but to be honest I would be at least 5K if not a little more to make the change..... or one that would live anyways :). curious.... did something "shake" when you changed your trans? Why do you think it's the trans and not the driveline?