1998 Explorer XLT possible axle issues?

[GreaseMonkey1709]

Howdy y'all!
I have a 1998 Ford Explorer XLT, with AWD and the 4.0 SOHC.
I've had a rather annoying humming noise that sounds like it's coming from the rear, gets louder and higher pitched as speed increases, and ONLY manifests itself when throttle is applied. I am aware of a recall (I guess) that Ford put out way back in the early 2000's, that addressed some sort of axle pinion issue. not sure if that has anything to do with my problem (if anyone can find that documentation, I'd love to give that a look, as I don't know the details on that recall).
I have checked driveshaft ujoints, though I may preemptively change those for maintenance. I have done an oil service on both diffs, with Fords LS3 additive in the rear. Only thing I have not thrown parts at yet are the rear shocks, as those COULD cause noises, but there are no indications that those are failing.

Does ANYONE have any knowledge on this? Is there a known issue that I'm not finding? If it does happen to be the axle, would getting the rear axle, with matching gearing, out of a later gen Ranger be a good idea?

Thank ya!

 

[Rick]

The Ranger axle assembly is different from the Explorer. It's not a direct swap. U-joints is something else to check. If you disconnect the driveshaft you should be able to check for roughness in the differential, axle and pinion bearings.

 

[GreaseMonkey1709]

The Ranger axle assembly is different from the Explorer. It's not a direct swap. U-joints is something else to check. If you disconnect the driveshaft you should be able to check for roughness in the differential, axle and pinion bearings.

I'm aware of the housing differences. If it comes to that, I may attempt to weld the different mounting points on there and make it work (famous last words)
I disconnected the driveshaft a while back when I did the dreaded timing chain repair on the 4.0sohc (pain), and didn't notice anything immediately, but I think I'm gonna get under there again and check again...