TJ: NP231 Bent output shaft?

[TJ Jake]

I've been noticing for a long time now that my LJ has had vibes at ~30 mph and ~55. So first thing I did was replace the u-joints, and that didn't help. So I had it up on the lift (community college auto class) and noticed the drive shaft was a little wobbly when I had it in gear and the rear tires spinning freely. I don't think the drive shaft is bent, it has no marks from hitting anything nor are any of the weights missing. The yoke on the axle is tight and my u-joints are still very good so I'm starting to believe that my output shaft is bent.

My question is, how did I bend the output shaft? And where is the best place to get one? I know ideally it would be best to get an SYE/CV set up now so when I do get a lift all I'll need to do is re-adjust the control arms, but I don't have 500 bucks to spend.

[2blk2drs]

Pull the driveshaft, you can roll it on a bench and check it.

Also while the shaft is off, put it in gear, and check the output shaft to see if there is runout.

[guardian7]

Just remove the rear drive shaft and run it in 1st gear, you should be able to see the output shaft wobble if it's bent without pulling the xfer case apart. Some specs on your Jeep would help too? Anyone who has done the SYE has an old shaft laying around or they tossed it in the trash like I did.

[OU812]

Also check if the slip joit in the driveshaft doesn't have any side to side play.

[6spdYJ]

A bent shaft would always shake and get worse with more speed. Check your driveshaft angles.