I had a shop change out the three drive-shaft u-joints and lower the center bearing 1/2". On the way home it was shaking between 35 and 40 and again during decelleration. I decided to remove the 1/2" spacer.

I measured the spacer and they had actually installed a 5/8" spacer, not a 1/2" like I had asked for. Not only that but the nuts and bolts they used for the center bearing were not hardened steel and they didn't put lock washers on them. For this I paid $292! ($56 for each u-joint plus labor, etc.)

Removing the spacer fixed most of the shake. Of course I replaced the nuts and bolts with ones of hardened steel and added lock washers.

I've learned my lesson. Next time I'll do it myself.

Just remember to double-check other people's work to make sure they take care of your investment like you would.