Problem: Drive shaft rumble/shudder upon initial acceleration.

It looks like we will have to pursue the "shorten the driveshaft” option to resolve this problem of drive shaft rumble/shudder upon initial acceleration. The question is – how to determine the correct reduced length? If only 1/8” to 3/16 length reduction was required, it appears that could be achieved by machining the face of the transmission / driveshaft coupling.

U-joints and carrier bearing have been replaced with no material improvement. Shims were also placed under the carrier bearing. I am now replacing the tail shaft bearing. The coupling into the tail shaft shows considerable apparent wear and simply replacement of the bearing may no resolve this loose fit — I am also considering repair or replacement of this transmission / driveshaft coupling.

Your comments and recommendations?

Curt