Driveshaft destroying my rear axle?

Came across something very strange while trying to diagnose a front end noise today. The slip joint in my rear driveshaft is totally seized. It's a factory front shaft used with an SYE. When I took the shaft out, I couldn't collapse or extend it by hand. It took a vice and a 4 lb sledge to finally get the two halves to move apart slightly. No grease, and lots of corrosion.

This make me wonder, when my suspension was cyling up and down, where did all that force go? The shaft is supposed to be compensating by extending or retracting. Something had to give? About 6 months ago my rear diff started making noise, and it's only gotten exponentially worse. I figured with 175k miles it could be any number of bearings going bad. But now I'm thinking the seized shaft could have been putting a lot of stress on both the axle and my transfer case. With the rear shaft out I wiggled the yoke clockwise and counter clockwise checking the backlash, and the yoke rotates a LOT. Way more than the .015" spec or whatever that it's supposed to have at setup.

Twisting left and right is normal. Up and down is not. Backlash is the amount of room between the ring and pinion. What you are feeling is just the slop in the spiders and other areas. Totally normal. The movement would have been taken up by the rubber in the motor and trans mounts. Not good.

Ron

Yikes, that's what I was thinking. After removing the shaft and taking it for a spin around the block, the ride was much improved as well. I have a new rear going in next week so I don't care about the axle, but I'm really hoping I didn't destroy a bearing or something in the t-case.

Take the zirk fitting out and them try to move it. Could be it is totally full of grease and the seal is extra good.

If it is totally frozen remove the zirk and squirt some penetrating oil in there.

All that force went into the motor and trans mounts... through the rear tailcone of your SYE, and possibly the rear output shaft and transfer case housing bearings, depending on what interferes first.

If you had a stock transfer case in it, you'd probably be looking at replacing the speedo gear housing / rear output housing right now, like I had to a few years ago when a lack of bumpstops and a bad case of leaf wrap bottomed out the slip yoke on my '96 and shattered the pocket in that housing which the rear output shaft bearing seats into. Fortunately the SYE housing is a good bit stronger. It might still be wise to pull it off and take a look at the housing where the bearing seats into it to make sure it didn't fracture.