Re-gear education please.

[YY1]

For comparison, here's the Auburn cone type:

 

[Cranky]

Does that have cones in it or discs? That unit looks very similar as the present day Trac Loc that comes in the 9 1/4 and other rears which use discs....and they suck for the most part but that one may be better. Can't say since I've never ran one. Had a new one and after carefully looking it over, I passed it on to the next person. I like the factory style Borg Warner cone unit over that one. I have a Trac Loc in our 2000 Durango and at 25k miles it started chattering so I changed the oil, cleaned out all the crap that was in the bottom of the housing and added a bottle of the SureGrip additive that's recommended and within 5000 miles, it was chattering again! Went through the same thing again and I'll be damned if it wasn't chattering again to the point I thought it was coming apart but it looked fine so when I put new oil back in it with a half bottle of STP. That was 30k miles ago and all is fine.

 

[YY1]

It's advertized as a replacement part for the 8 3/4 and looks like the one in my brother's 489 case.

You may have something. I didn't know there was one like you describe.

Now I will need to look in more detail......

 

[Cranky]

I don't have a complete original cone type carrier laying around right now but I might have a pic on my puter somewhere. Had a bunch of pics on photodump.com before they cratered it all...anyways, they are similar with the biggest difference being that the new one is a one piece carrier whereas the factory unit is a two piece setup. The original has a small window, the springs are closer and maybe the spiders and side gears are a little different (smaller?). With the new one, you have to load all the parts through the window and if it's anything like the Trak locs, it's more of a hassle to load it up. With the old one, you stack it all up on one half, the place the other half on on and then tighten the cap screws up a little at a time evenly. All you have to do is make sure the axle splines are aligned up with the side gear and cup since they are separate pieces. I have a couple of home made tools made from a couple of axles they are big T handles. One gets placed in a vise with the splines sticking up a bit and then I put one half of the carrier housing on it and then start stacking. The spline on the tool keeps that half in alignment and when I put the other half on the stack, I put the other T handle in it and aligned the parts on the other side.
Here's the T handles with a SureGrip carrier stuck on. I also use these to check how tight a unit is. Just step on the handle on the ground and then grunt on the handles sticking up. If it's really hard to twist, it's good to go but if it's easy, it needs to come apart and worked on.