Would appreciate some insight from those who have been there-done that with rear gear changes. Have read many posts on this subject, but still need some clarification.

Want to replace stock 7.5” 10-bolt 2:41 gear Open carrier with:
- 28 axle-splined III Series Posi-carrier (Eaton?)
- 3:42 or 3:73 gears for above III Series Posi-carrier (Richmond?)
- 28-spline axles (Moser?)

Some questions:
1. Will proper length 28 spline axles fit into a housing that originally had 26 spline axles without any modification to the axles or housing?
2. If replace II Series Open carrier with III series Posi-carrier, are the gears needed the same as if I already had a III Series carrier, or will something else be needed since a III carrier is going into a housing that previously had a II carrier? Always confused on this!
3. Are manufacturers above OK, or are there better recommendations? If other recommendations, would appreciate why.
4. Anything omitted, or something else I should be aware of or look out for other than seals, bearings, new retaining bolt, other new bolts, trans speedo gears, etc.?

Thanks!

 

All of the housings are the same. It doesn't matter what gears came in it or what series the differential is, they are all the same. If you use 3 series gears and a 3 series Eaton Posi you will not need to make any other modifications. The 26 and 28 spline axles will interchange with no modifications. They both use the same axle bearings, seals and c clips. My recommendations for parts would be Eaton Posi, Yukon gears and installation kit and Yukon or Moser axles.

You are going to need to know how to set the pinion depth, bearing preload and backlash to install these parts. You also must know how to read the contact pattern so that you will know what adjustments need to be made to the pinion depth and backlash. There are a few special tools needed for this job.

 

I just noticed that this is probably for a El Camino, which means that you will be going with the Moser axles because these will have to be custom made.

 

Big gear head - Tks for the prompt reply. Your tips are right-on about installation. An ASE GM tech that does this during his day job will be doing the work.

Also right about El Camino ('84 = G-Body), and I should have mentioned that given this is a F-Body forum and housings are different, aren't they? But, I don't understand the issue with the axles:
- Do they have to be specially made because of 28 splines, or are there other issues?
- Is Moser the only one that makes them (28 spline for Elky)?

Also, could you elaborate on why Yukon gears over others.

Thanks for sharing your knowledge!

 

You are going to need custom axles becasue the G body never got 28 spline axles from GM. The 7.5 rear end was upgraded to 28 spline axles around '90, but the G body was already gone by that time. There were no factory installed 28 spline axles for it, so there are no 28 spline replacement axles either. Moser has made many custom axles for me and they always fit the way they are suppose to.

I've been dealing in Yukon gears for several years now and their quality is as good as any. Everybody makes a bad gear now and then, and Yukon has been as consistant with their quality as the others. They also install thier own products, so they see problems as they come along.

 

Thanks again!!!

 

Another option for you would be to get a used rear end out of a 4th gen camaro with zexel torsen posi and the gear ratio of your choice. Take the guts out of that rear, get new custom axles and put it all in your original el camino housing. This is basically what I did with my camaro and it saved me some money.