Rear diff pinion shot, need ideas

[Sean Foster]

So I’ve got a 91 80 series and I’ve realized recently the amount of pinion movement in my rear diff is… insane. I’m thinking of getting it rebuilt but if I can find a third member and just slap it in I’d be happy. I know it’s a 9.5 and was wondering what all trucks could I possibly scavenge a 3rd member out of. Also curious if the 80 series full floaters are even the same 3rd members, I don’t think so but I could be wrong.

 

[Road Apple]

One possibility is to install a ‘95-97 axle housing. Then you get rear disc brakes and full float.

Or re-gear your existing diff and save on buying a third.

There’s a bunch of discussion on 80 series thirds here. Looks like non-locked thirds are interchangeable.

3rd Member Interchangeability?

forum.ih8mud.com

 

[White Stripe]

So I’ve got a 91 80 series and I’ve realized recently the amount of pinion movement in my rear diff is… insane. I’m thinking of getting it rebuilt but if I can find a third member and just slap it in I’d be happy. I know it’s a 9.5 and was wondering what all trucks could I possibly scavenge a 3rd member out of. Also curious if the 80 series full floaters are even the same 3rd members, I don’t think so but I could be wrong.

I would buy a whole full floater rear axle assembly. It's a time consuming swap, but very easy. Worth the upgrade.

 

[Sean Foster]

I would buy a whole full floater rear axle assembly. It's a time consuming swap, but very easy. Worth the upgrade.

I would if I had the money laying around, at the moment I found a semi float fully assembled for like $400 and it’s in town. If you or anyone here knows a full floater laying around in the Colorado Springs area i would be highly interested for sure tho!

 

[White Stripe]

I would if I had the money laying around, at the moment I found a semi float fully assembled for like $400 and it’s in town. If you or anyone here knows a full floater laying around in the Colorado Springs area i would be highly interested for sure tho!

You should be able to find a full float for 300 or so. Do you have a business you can ship a pallett too?

 

[Sean Foster]

You should be able to find a full float for 300 or so. Do you have a business you can ship a pallett too?

Possibly, depends if my work will allow it but gov jobs tend to be a little more iffy on that

 

[Sean Foster]

You should be able to find a full float for 300 or so. Do you have a business you can ship a pallett too?

Also everything I’m finding that’s full float is like a grand at least it’s stupid, also would I have to swap the master to a newer one since I’m going from drum to disk?

 

[McFabLC]

You should be able to find a full float for 300 or so. Do you have a business you can ship a pallett too?

If you can find $300 ff axles let me know where please!

To OP, all 80 series are 4.10 ratio from the factory so any non-locked 3rd is interchangeable.

The factory ring and pinions are of very high quality so most of the time, just rebuilding with new bearings is enough, without the need to buy new gears if you wanted to go the rebuild route.