Engine/drivetrain vibration?

I'm no expert on 340's, but I thought that I read somewhere 72 340's were steel (forged) cranks up to April 72, and vibration dampers changed on 04-11-72 from forged to cast type... On big blocks a cast crank meant a different vibration damper (says on it for cast cranks only and usually larger in size) and the automatics came with balancer weights on the torque converter and were matched to the engine in that position, only (the torque converter has 4 possible positions with the flex plate)... Also, on the big blocks an E was stamped on the engine ID pad to mean a cast crank... So, if you bought a 440 with an E stamp, you better get the torque converter with it... Hope this helps, good luck...