Rear Differential Giving Troubles

What do you mean by dropped all the oil..???

They just dont just drop 4 gallons of oil.
Where is it leaking from????

Your mechanic could be correct. If it just recently had a rear end swap and the wrong ratio was installed then they work against each other and over heat. This will cause oil to blow out the vent or leak through various seals.
If this is the case then the damage is probley done and now your probley looking at both rears to be replaced.

Not sure what else would cause the oil to get that hot.

 

You can ck rear end ratio the old faction way by jacking up each side of rear end then marking each tire and u/joint cap then spin each wheel 2 times and putting in your note book where ujoint stops at then do same on other wheel to see if after 2 full turns u/joint stops at same place doing it a few times,! but not having gear set up to spec will make rear end puke after a short time, if you drove on dirt you can see tires sliding

 

Unless you've got a leak, the oil didn't go anywhere and a pail of oil being sprayed along the frame and trailer will be pretty noticeable and probably pretty easy to locate the source.

Lockers weren't locked in? If its got a diff lock (not inter axle) it would have to have been locked in to remove the carrier assembly at replacement. Can be done with the switch on the dash or with a bolt through the air fitting on the actuator.

 

We have seen synthetic oil get so hot it just burns up and turns to ash and basically does in effect disappear inside the housing.

 

Wow, those internationals must really have some jam!!! Jk.

 

Wait ....

This mechanic didn't check the gear ratio before he put in the pig for the bad axle?

He should be paying you for the down time and the mistake he made and refund all the money you spent on the "repairs".

 

The last reman I put in had a different ratio on it. Paint marker had the ratio I had ordered and I checked it. It was correct. Five years later the paint could be gone.
Spider gears double the number of turns one jacked up wheel turns, allowing for gear ratio, compared to driveshaft. Example on a rear rear with a 4:00 ratio is turned 10 turns of the jacked up wheel the driveshaft would turn two turns.
The front rear has two sets of spider gears. One in the carrier and one in the power divider. One wheel jacked up and rotated 10 times the driveshaft would turn 1 turn.
Start with jacking up one wheel and making sure the P/D will disengage. With transmission in neutral that wheel set should turn.
You might want to double check that on another truck but I thank that is correct.