I recently replaced my rear 3rd member and have since noticed a slight wobbling sound in the rear. It's not very loud and doesn't cause any vibrations I can feel. It's something a passenger might not even notice, but it drives me crazy.

I can't be sure if the wobble was there before the swap, because the 3rd member I swapped out was very noisy and could have been drowning it out. Also, I took the truck off roading only a week or two prior to the swap, and beat the hell out of it, and if I bent something then that started this wobbling sound, there's a very good chance I wouldn't have noticed it until after the swap.

Another clue is that the right rear axle shaft was a bit difficult to put back in. The left one just slid right into place, but the right one wouldn't go into place until I cranked down the 4 bolts holding it in. This isn't necessary the shaft though. Could my swapped in 3rd. Or maybe it's normal for this fit to be really tight?

Removing the rear driveshaft and driving around on the front wheels doesn't get rid of it.

I'm at a bit of a loss as to how to proceed.

I'm thinking I'll eliminate possible culprits by swapping in good parts, in this order:

1. wheels/tires
2. axle shaft
3. 3rd member
4. wheel bearings

Any help on this is really appreciated.