A buddy of mine gave me an old jimmy he had sitting in his yard as I needed a vehicle, the only real problem is the rear diff is busted on it. We're not sure what's wrong exactly, all we know is that there's no power to the rear, they had to put it in 4WD to get it home before they parked it there. After a whole lot of research, i'm pretty sure I can just replace the diff myself, but I can't find any specific info on this particular vehicle or ones similar to it.
The most informative video I found was this one: where the guy replaces the rear diff center on a Toyota Landcruiser. Would this be similar to the method of removing and replacing the diff on a jimmy? or would I need to actually open the rear diff up and remove the diff itself then replace it that way.
I'm not the most mechanically inclined, but once I know how to do something I can usually do it pretty well, so any help is appreciated, thanks in advance.

 

Can you post a pic of the RPO-code label in the glove-box.
That way we would know what type of rear and differential is in the Jimmy.

 

Turns out it moves in 2wd or 4hi and won't even go into 4lo so that was some incorrect information I was given there. I opened the diff up to see if i could see anything and it was mostly empty aside from some oil that smelled and looked like it was excreted by satan himself. I felt around inside and It was full of large metal shards and bearings, so i'm going to guess that one of the bearing rings exploded.
All I know about this diff is the gear ratio is 3.42 as seen in the RPO code, any help is much appreciated.

 

The rear differential in your 92 is a GM 10 bolt. It's a 7.5" or 7.625" ring gear. Watch you tube videos for the 10 bolt with a crush sleeve.

 

I'm seeing a lot of videos with "8.5" rear axle" in the title, i'm guessing the 8.5" is referring to the ring gear size?

 

Yes. The inch measurement is the diameter of the ring gear. The 10 bolt cover differentials are basically the same but the larger 8.5" has a larger, different shaped housing (case/pumpkin) and carrier.

 

From the videos I've watched, if the gears aren't damaged, all i'll need to replace is the destroyed bearing/s, both seals, and the crush sleeve, does that sound right?
From the looks of things if i'm lucky this may be a much cheaper and easier job than I thought. The more rebuild videos I watch the more confident I get

 

That's the point. You're correct. There's just details that make it a bit of a pain. For instance, there are 3 seals and a cover gasket. Pinion and left and right axle seals. The ring and pinion gears are not damaged, they're worn out. You got this. Any questions, fire away.

 

I'm not the most mechanically inclined, but once I know how to do something I can usually do it pretty well, so any help is appreciated, thanks in advance.[/QUOTE]

Replacing the ring and pinion gears in the rear is going to require specialized tools and knowledge. You would be better off replacing the entire rear axle housing with another, from the salvage yard, that matches the ratio of the front axle.