A-body 8 1/4 questions : rear gear set swap

Some where online, I read that an A-Body 8 1/4 rear end with hi ratio (2:45) gears will not accept a set of 3:55 gears because of a 7mm off set machined in to the housing. The housing # cast in is 2852905.

Is this true?

Also will a set of 3:55 gears and limited slip work from a Dakota work in the A-body 8 1/4?

The carrier is different between the two. I think the cut off was around 2.71 ratio. I think many years ago you could buy a spacer but I would not use one even if it was available. Also I`m pretty sure the axle spline tooth count changed on the later years but I don`t remember what year. I`m thinking 96.

2.45 and below uses a unique carrier, anything above uses a different carrier. I seriously doubt the 7mm thing though since they didn't do metric back then.

I have a NOS sure grip for the 8 1/4 with 2.24 - 2.45 ratio.

IIRC, the issue you run into when going to the 3 series gears is the ring gear hits one small area of the case, and that can be ground out to clear.

Ok Thanks for the reply's. I was wanting to work on the rear end his weekend but it looks like I'll be changing out the water pump on the wife's daily driver.

My plan is to take some pictures and post of the fitment and any issues.

I was able to get the water pump changed in the wife's car in less than a day.

Spent a little time with the rear end.

Found some things:

This has been the only rear end that I have worked on that I did not have to straighten. Alignment bar went right in.

The limited slip I have from a Dakota 8 1/4" has larger carrier bearings than the Darts 8 1/4" rear that I am building. Hope to find some bearings that will make it fit. Worst case scenario I machine down the bearing fits to the dart size.

The limited slip did not rub anywhere on the housing like thought. Its tight, that's for sure. More attention will be payed with further assembly.

The pinion had no interference's with the housing.

I have decided to build a hot water parts washer to use on this rebuild and future rebuilds. So this rear end rebuild will slow some.

IIRC, the car bearing will fit on the truck carrier. I went through that on one I did.

Hopefully I be able to get some time in on the rear tomorrow.

Found this thread with lots of 8 1/4 info.

https://www.forabodiesonly.com/mopar/threads/the-8-1-4-thread.350667/

hi con, double check axle splines on that sure grip. the older sure grip with the 27 spline uses Timken LM102910 1" 25/32 id bearings and LM102949 2"57/64 od races. the newer 8.25 29 spline uses Timken LM603049 bearings and LM603012 races. ronnie