The weight on the side is never touched. If you took off the 2 big weights from the front flat face & it still vibrates then I'd get another torque converter as you have now tried it with the weights on (external balanced) & with the weights knocked off (neutral balanced) & no go either way so unless there's a balancing bobweight difference between a neutral flywheel and a neutral TC and or if there's a difference between an external flywheel and an external TC & I dont think there is then it has to be the TC & the only difference from when he had it & it ran smooth & now that you have it & it dont run smooth is that it had a flywheel & now it has a torque converter. It may very well have been still externally balanced like OE (& most hotrodded 360's are) & now just needs the correct externally balanced converter which if the front dampener is the (360) offset unit then I think that's the case (external balanced). Holler how it turns out. EDIT external 360 on the right side/neutral 318 on the left. You wouldn't think they used mag parts here which skews things since as said the externally balanced 5.9 (360) mag & non mag (early regular 360) externally balanced TC's are weighted differently from each other even tho both are externally balanced & in addition you have tried it with the weights on & off & no success. post what you have for the dampener. A 360 could have been neutral balanced with the offset dampener but people usually go with a neutral one if they are going to the trouble (& $$$) to neutral balance a 360