Engine/drivetrain vibration?

Thanks for all the replies. Let me see if I have this straight. My shop is about 99% sure that the balancer is original and correct for the cast crank '73 340 that's in the car. They also think the new TC that was installed during the tranny rebuild is the wrong one, and have subsequently removed all the balancing weights from the TC. I guess that means it's now a "neutral" unit? Are you saying that I can keep the current TC, without balancing weights, by simply installing the correct B&W flexplate for the cast crank engine? If so, do you know of a good source for this flexplate?

From everything I've read, it sound like the correct TC for this application should have weights. Shouldn't I also be purchasing a correct TC (either in addition to, or instead of, the B&M flexplate)?

This problem sounds like a total snake pit! If the TC problem is not the source of the vibration, then what? Geez, I hate to pull the rebuilt engine out of the car (that's about 100% show ready now) and starting tearing into the internals. :pale: