Short version is a mechanic we were referred to in order to diagnose a shake around 60mph claimed the front two u-joints and the rear u-joint just after the transmission were on the way out. He also claimed both rear wheel bearings were bad.

When asked how the u-joints on the front shaft could be bad in an X that's got 99k miles but has rarely been put into 4wd he said that shaft turns all the time and the engagement is made in the front differential. He's full of it right? That's pretty much the worst design I've ever heard of.

We're pretty sure it's just the u-joints on the rear drive shaft that are going bad. We also doubt both wheel bearings have managed to fry themselves at the same time this problem creeped up.

EDIT: We also can't find any controls going to the front diff or figure out how anyone could fit the mechanism to engage the gears inside the pumpkin with a differential into it. Therefore... we think he's full of it.

yes he is!! but the front drive shaft will turn while you are driving it in 2 wheel drive.usually it is the rear u joint in front drive shaft and front u joint in rear drive shaft. the transfer case is what locks to cause 4x4 engagement but laws of gravity cause the front shaft to turn.have not seen rear wheel bearing go out in pairs have seem fluid leaks thow.

Ah, didn't realize gravity would be enough of a factor to get the front shaft turning in two wheel drive. Regardless, if that's the case, and I don't doubt that it is, there's no way it'd be turning as fast as the rear shaft when 4wd isn't engaged.

I just can't see how the front shaft would be the problem right now. Once we get our money making equipment working again I'm going to tear into the rear shaft. Probably Monday at this rate.

Thanks for the input!

I would do the front drive shaft rear u joint look at it u will see it loose our rust coming out of it