So I know I am new here and I have spent entirely too much time trying to find what I am looking for.
So here we go, my friend bought this 00 550 7.3l 6speed 4x4 I know kind of a unicorn that is why I told him to buy and the price was to cheap not to due Cali kicking out all the 7.3l this year.
So I was checking all the fluids and when I pulled the fill plug on the rear end it was very contaminated with water. Yeah the worst thing you can do for the most part. So after about 1.5hrs of digging the dirt of drain plug and manipulated the metal in plug so I could get the tool in the drain plug out I get it out and the fluid just barely comes out and I look up and there is something in the hole so I push up on whatever the obstruction is and the nasty fluid comes pouring out but the big problem is what was the obstruction is.... I mean in my experience that is a very bad sign. So after at least 1 of trying to get it back of to hole and cleaning it off well enough to see what it is. I finally figured out it is a head of a bolt and it is just a little to big to come out the drain hole. After what I can find is this bolt is most likely a ring gear retaining bolt. As near as I can tell this is not a common problem with these rear ends. Can anyone give me the rundown on why or how this could happen please and thank you. I have losing my trying to figure this out going down the google machine's 🐇 🕳...

 

I'd have to agree with you there. Never heard of that happening with the Dana S-135. I've had no issues with mine for the last 21 years.

 

I finally figured out that it is one of case bolts. But I was a jack *** late last night and was trying to fish the bolt head out and friend gave a small long Allen wrench to it and somehow it just kind of got sucked out of my fingers and now I am trying to get that thing out of and can't find it. I could touch it with my middle finger last night but got away from me and now I a flexible magnet but I can't locate it. It felt like there was a magnet in the housing somewhere that took it away. This about 5 hours of laying on ground rain and cold wind. I am super happy 🤨

 

Sounds to me like you're going to have to drop the driveshaft and pull it out of the housing. At least that's what I would do, you have a bolt head from somewhere and now an Allen wrench in there, I'd open it if for no other reason to see the condition of the gears.

 

Well after further inspection I have found 3 of case bolts are broken. And Dana has discontinued the s135 and finding one a replacement isn't very easy. I found a place in Florida that has a rebuilt unit for a even remotely affordable price but I don't think it is a locker. But I will find out more in the morning when I call I am just hoping the shipping isn't $2000. Does anyone here have a link for diff's for these trucks?

 

Here's one I found but don't know anything about the company selling them

https://truckpartsinventory.com/rear...ana-s135-parts