I've been hearing a bit of a whine from the drivetrain for the last six months and it's been getting louder so it was time to investigate. During this process, I noticed the rear DS slip yoke just had too much play, after 26 years of use so a new DS went in. One of the craziest/stupidest thing I've done to date is to jack up the rear wheels on jack stands, then drove in place at 60-70mph. Using a mech stethoscope, I tried to locate the source of the whine. I'm rear WD and parked the rig against a tree but still, those 315s rotating at 60-70mph was unnerving to say the least. The throttle control cable had to be used and it took a while for the transmission to upshift into OD.
Since the noise could be heard inside the cabin, i started with picking points on the Tcase/transmission and heard nothing of interest. Smooth and quiet, granted this is an unloaded situation.
Moved on to the rear axle housing and did find one of the wheel bearings louder than the other one. So, that was one potential.
Moved on to the rear diff - carrier bearing area sounded normal-ish but the outer pinion bearing was WHOA. She's a noisy bugger, WTH?
So, the rear axle housing was stripped of everything. 3rd member came out and placed on the makeshift diff holder that I cobbled up together and used the engine stand. First sign of something was up, pinion bearing pre-load was ZERO.

So, the diff tear down began and the second scary moment was when the outer pinion bearing simply slid off vs getting pulled off.

I pulled out the 4.10 pinion out of the shed and tried to slip on the outer pinion bearing on to it and she wouldn't slide on at all. Next thing was to compare both pinion shaft and it looked like the pinion bearing might've spun in place.

At this point, a master rebuild kit, wheeling bearing kit and a solid spacer were ordered from Cruiseroutfitters. After consulting Zuk @
www.gearinstalls.com, it was concluded that the pinion lost its pre-load maybe due to the crush sleeve losing it's ability to keep the two bearings apart and maybe this was due to age or maybe due to my amateur 4.56 gear install back in 2005, who knows. Zuk said that a sliding outer bearing is not a huge deal breaker as a new crush sleeve/solid spacer may prevent it from spinning with the application of the correct Loctite. However, he has changed his position on using Loctite on the pinion bearing. Zuk didn't like the gear marking paint pattern and suggested a new R&P oughta be used for the "correct" pattern. Ordered R&P from Cruiseroutfitter and sent everything off to Zuk using an awesome diff box that a local buddy had in his garage. I also included two near ARB O rings in this package but it turns out that my locker RD-33 is so old that the new O rings are too large anyway. Total weight of box including a master install kit was 92# and it cost around $90 to ship it to Zuk using UPS and the promo code EASY for a little discount.
So now she sits on the driveway, with a naked rear axle housing....
4.10 pinion on the left, bearing doesn't slide on
pinion bearing slid on/off too easily on the 4.56 pinion, possibly a spun bearing