There are various seals in a differential assembly. Any one of these could be bad which isn't a big deal. Just needs to be replaced.
It is not the brakes leaking oil , Its the axel seals leaking rear end gear oil. If its not gear oil , Then its brake fluid and that means wheel cylinders are leaking.
The rear main is on the end of the crank shaft. The transmission and flywheel have to be removed to service.
I would say it was Lee Marvin. He served in the Marines in WW2 and was shot in the rear.
You can tell your rear engine is leaking by looking under your rear engine and see if there's drops hitting the ground.
It may have water in the rear diff or over filled the oil. Drain the rear and refill. Hopefully you get just oil.
If the antifreeze is leaking out the exhust system, I.E. you are experiancing white smoke, you either have a leaking head gasket or a warped head. I can't see any other areas where there would be antifreeze at the rear end of any explorer model.
There are 2 rubber seals on each end of the wheel cylinders and there leaking. REPLACE THE WHEEL CYLINDERS.
I'd say your ring and pinion is shot. You need a new rear end or rebuild the one you have.
You'll see either fluid or grease leaking out of it.
your main oil seal on the rear of engine is leaking or the timing cover seal is leaking,
NO!!
it is usually the rear brake cylinder that's leaking and needs to be replace on that side.