So, I was driving up to Coeur D'Lane today when I noticed a sound that reminded me of a little man under the back of the truck swinging a small hammer on the rear diff....
Considering I was on the road with no tools, I decided to push onward until I could get to the nearest Napa or AutoZone....

Fast forward 70 miles... The little man with a small hammer has turned into a little man with a 20lb hammer.

Pulled into napa, bought tools and gear fluid... went to inspect the issue... it was BONE DRY. Crap. Filled it, capped it, started to drive home...

Sound went away for a few miles, but was right back again shortly. Drove it back home, stopped for gas and to top off the rear again. Fluid was covering the undercarrige. Looks like it's leaking from the pinion seal.

Made it home (220 miles round trip) and it literally ceased in the driveway....

So, looks like I need a new 3rd member.

What else should I do while I have the whole thing apart?

 

You might need to replace every bearing and seal, including the axle bearings/seals. Reason: metal in the gear oil went through the entire thing. And lots of cleaning in the housing from one end to the other.

 

That is a great idea. Thanks bswarm!

I forget, the axle bearings have to be pressed?

 

Sorry about that.
You remember the last tie you did maintenance / replaced/topped off the gear oil?

I would rebuild.

 

I have literally owned this for a month. Had the 3.4 swap done, so it was gone for 2 weeks... so in reality, I've been driving it for 2 weeks. When was it last done? Who knows. I know the 3rd is bad now, I plan on replacing the entire 3rd, not rebuilding.

I was trying to determine if, while the 3rd and axles are out, I should do anything else.... like a rear disk swap... or re-enforce the diff housing.. or (insert other mod here)

 

Well... I'm now in the market for a 4.88 rear diff, and a 4.56 rear diff for another project! Anyone have either one of those?

 

Lets see some pics of the damaged diff when you get it out! Good luck on the 4.88 search.

 

I have a feeling it looks like a bomb went off

 

personally i would do: brand new 3rd with gearing and locker of choice, new bearings and seals for axles, low-profile magnetic drain and fill plugs, barbed breather fitting with hose extension and pod filter.

consider: rebuilding ujoints/entire drivelines, brake upgrades and/or full-float upgrade, trianglulated shocks/ubolt flip, housing armor/trussing.

 

I would just find a good junkyard diff and stick that sucker in there. In my experience these rear ends are plenty robust for normal use, even with a gazillion miles on them. Yoda Jim usually has some 4.88s in his yard in Denver and regularly ships parts. I want to say they're around $250.

That route avoids replacing all the bearings, setting up gears, spending tons of money, etc... I would probably do the axle bearings since the whole thing could be full of metal. Or it might not...

 

If you want to run stock gearing in the meantime I have a third that I just pulled outta my 86 4cyl because I regeared to 4.88. I know it's not what you're looking for but it'll get you back on the road.

But at the same time, I'm gonna agree with the idea that a newly built third is the way to go if you are going to put a locker in and regear. They come with backlash/preload/pattern already set, new gear ratio, bearings, etc. and it usually ends up costing about the same as just those parts would cost individually. But of course, then you gotta find a 4.88 front (I got mine at yota Jims)

Edit: looking back at the other responses again, it's easier to just say "^^^ do what highonpottery suggested a few posts ago"

 

^you can also buy front 7.5" IFS diffs the same way. not as many places carry them as the 8" diffs, but they exist.