Was replacing rear brakes and found my drivers side axle was leaking.

Axle tag reads
S 918 A
3 55 9 75 9A12

I've gotten the axle, seal and bearing out. I bought bearings that are supposedly for the 9.75 and they do not even come close to fitting in. Now I just happen to get bearings and seals for the 8.8 just in case and they appear to be the right size, but the bearing looks slightly different, wider with an o-ring on the extended part and a seal inside the bearing. It appears if it were driven it it would stop where the old seal was and the additional part of the bearing housing would be were the old bearing was. Also making it not possible to put the new seal in. Anybody know whats going on here? The parts store guys said I had the right part.

 

From that code, you do indeed have the 9.75. That means your truck has a 5.4L engine and all 5.4's have the 9.75. Anyways, you need to try another store. That store doesn't seem to have the right part for your application.

 

Parts guys at local auto parts stores have their heads up their asses quite often. I had one guy who couldn't pull me up a gasket for the 9.75 diff cover, and "only" could get one for an 8.8. right... i would up using blue permatex, but the point is learn your sh*t b/c these parts stores will often send you the wrong parts leading to frustration, time wasted, and incompatibility. heed McLovin's advice.

 

It's all fixed now.

The bearing I described was an "axle saver" and is designed to put a new race/bearing into axle housing thats got messed up races. They have an O-ring to seal between the new race and the axle, and an axle shaft seal built right into them.

I ended up finding some regular bearings at carquest and using those since my stuff wasn't messed up. Figured I'd save the "axle savers" for when the axle needs saved.

But I still don't know why I have a 9.75 ring gear and 8.8 bearings. Both parts stores said the smaller bearing was for the 8.8, and thats what I had to use.

 

I ran into the same thing today. Tag says 3.55 9.75 but Napa pulled this huge bearing, went to the 8.8 bearing and it looks like the the stocker.. I haven't tried it yet but I hope it works.

 

FYI.

The bearing they pulled for the 8.8" ring, was the right one although my tag specifically denotes a 3.55 9.75" ring. I measured the ring and it's 9.75".

I picked up the axle puller set from Harbor Freight for $24 bucks. Worked like a champ. Yanked em out and use my seal/race driver to install the new ones and put the thing back together again, and filled the diff with Amsoil 75-140.

We're back on the road again..

Next up, new plugs..