Vibration help?

[Shawn Weaver]

Thanks for allowing me to join for help. I have a 1990 3/4 Ton regular cab 2500 2wd with a TBI 5.7 Liter engine and a TH400 Transmission, so no OD. The Problem: I get a rhythmic vibration from 30mph on up. It might be a little lighter under acceleration but always there. Probably most pronounced between 45 and 50 and maybe worse under deceleration. I have replaced center and rear joints the carrier bearing. Had the driveshaft balanced, and I just paid a shop 800 to replace the Torque Converter because they said that was causing it. I am trying to figure out where to go from here. The only slack I can find is in the tail shaft of the transmission but not sure how much is normal and shop said that would not cause it. Pinion feels tight and I just replaced rear axle seals and everything felt and looked good in the rear end…any help would be appreciated. 

[richard wysong]

Welcome to the Forum! Any vibration in neutral or change shifting to neutral while it's occurring? Was there any change at all after doing the converter? Sounds like the T converter, wonder if you got a defective 1