Time to do pinion bearings in the 8.25?

Recently I've noticed a whine from the rear end, only under load and generally only at highway speeds. Unfortunately this sounds like I need to replace the pinion bearings in my 8.25. I replaced a leaky pinion seal about 5k miles ago so I'm afraid that I may have overtightened the pinion nut, then again, perhaps the seal went bad because the bearings were starting to go, who knows. Supposedly its almost impossible to overtighten the 8.5 pinion nut by hand because the crush collar requires like 350ft-lbs, but again maybe I overdid it.

I've never done any diff work before so this is definitively a little daunting. Now this does give me a potential excuse to re-gear, or pick up new axles, but I would almost prefer to stick with what I have than risk getting shitty jy axles that need to be rebuilt anyways.

Any thoughts?

A little research shows that the jy's know people want 4.10's..

So I pulled my ds off the pinion yoke and tried to feel any play, felt solid, I put some force into it too. Pinion nut marking is still lined up with the mark on the yoke from when I did the pinion seal.

Been unsure about the proper fill level for the dif with Solid cover on it, I put in the factory amount, plus an extra half liter iirc which is what the guys at Solid told me was the proper additional qty. Added another half liter today just for good measure, will see if it makes any difference I guess..

I have a solid cover on my d30, I filled it to fill hole and it put drag on the drivetrain,, too much fluid!
Full level is a touch above the axle tube (inside of diff.) so fluid can run down the axle tube to lubricate the axle bearings when vehicle is on flat level ground.
I drilled and tapped a hole in the cover at factory level and filled it from the upper plug until fluid ran out of the new lower fluid level hole, you do NOT want to over fill it.
You need to use a pipe tap and a pipe threaded plug.

I drilled a hole and tapped it to  1/8"NPT and installed a  plug at the correct level on my Solid cover.
It's not how much fluid you put in,, it's obtaning the correct fluid level that matters.

Thanks Mark, how do you tell if you have excess drag? I can barely reach the fluid with my pinky through the solid fill hole, which if actually what the level was before I did the pinion seal. I don't know if it makes any difference but I do have shims to correct driveline angle so I was thinking the pinion bearings would be higher than normal for an 8.25.

When vehicle is in motion the fluid gets carried up ring gear and is thrown twards pinion so even if diff is angled the fluid will still reach pinion bearings.

My cover had me using an extra quart or so of fluid so I corrected it with a correct level plug.
I could feel rolling resistance with the extra fluid. especially when outside temps were low and gear oil was thick ( FELT LIKE IT DID NOT WANT TO ROLL)

Cool! I'm going to figure out where the fill is on my 8.25 based on pinky length and fill location. Also gonna give it a highway run and see if the noise is still there, based on various information I've gotten I don't think I'm way over. Its a constant hum that stop immediately when you let off the gas.

Remove the rear driveshaft and try it.
Do you have an SYE?
Is your REAR drive shaft angle correct ?

Good idea, I've never gotten a consensus on how fast you can drive in FWD only but that would narrow things down. I don't see what you can't go highway speeds but people seem to be afraid of that? I don't see a reason why you shouldn't, unless the tcase doesn't like to only be loaded by the front.

Has a hack n tap SYE, and running a double cardan DS which I believe is an XJ front DS. I didn't set it up but the PO runs a shop specializing in off road, Jeeps, Landrovers etc. and he did install shims on the rear axle, so I assume the driveline angle is correct, though I should probably find out how to measure to make sure.

This noise has shown up in the past couple weeks.

It will drive without the rear shaft.
check to see if the bolt at the hack n tap yoke is loose.

Pulled the shaft, completely eliminated the noise, although FWD is rather rumbly..

Cranked down the hack n tap bolt for good measure even though it wasn't particularly loose. Haven't put the DS back in yet to see if that made a dif but I highly doubt it will.

Sorry for the quality of the picture but it looks to me like the pinion angle is about right. I did notice the T case output was tilted down slightly in the rear, I assume that's normal? Not sure though.

Is the centering ball on the CV jiont wiped out on the rear drive shaft, that will cause bad vibes etc.
It looks like there is a new u joint there.

All u-joints replaced within the last 4k miles, I rebuilt the centering ball at the same time, though I couldn't get a new centering ball seal.. One of the u joints was completely toast, hence the rebuild. I'll pull my front DS and throw it in the back tomorrow to see if that makes a difference, the front may need a rebuild as well though, I have the u-joints waiting but I need the centering ball parts, and I want to find the seal this time around..

What with daylight savings and it being freezing lately I haven't had a chance to swap front and rear DS's. I did drive it 300+ miles this past weekend against my better judgement, noise went away for part of the trip and eventually came back, not any worse though.

A new noise has developed however, when the Jeep is cold it makes a weird noise from what sounds like the t-case area only when moving at 15+ mph.. I'm thinking maybe it is a rear DS component after all, centering ball comes to mind.

Does it sound like angry sparrows and does it go away when in 4wd?

Kinda sounds like angry sparrows, annoyingly it hasn't been cold enough to happen since the first two days that it did. Something that feels like its more towards the front is getting rumblier than usual.. Gotta get unlazy after work tomorrow and pull the shafts, check the u joints, pinions and output of the tcase for any looseness. I hate feeling like I need to fix stuff but not knowing what exactly. Just gotta turn the music up and pretend that ignorance is bliss.