Decided to do a rear differential fluid change during time off and discovered yellow foam and thick thick fluid. Any ideas as to why it how this happened? Also, how does the diff look?

 

new gear oil has foam inhibitors, once those are gone/used up , the oil foams because of the shear between gears. Foam can also be caused by certain additives.
looks fine, just change it and go!

 

What should I clean it with? I've heard break cleaner and a hose. Or should I just leave all that **** in there

 

you can use brake cleaner, just make sure you get it all out of there. or you can just leave it as is and fill it back up. whatever you want

 

Sweet thanks guys!

 

How does a Ford 8.8 sound as a replacement for the 27 spline c8.25

 

Could also be memories of water in there. Brake cleaner, RTV that sucker back on, and check the vent hose and axle seals to see if they're ok.

8.8 sounds like a great replacement for a 27-spline if you've got the fab skills. Try not to hijack threads like that please

 

I was just about to say that. My rear end fluid looked like a chocolate milkshake a few weeks ago; ended up having water in the thing. I'd clean it out, seal it up and refill it, and then recheck it in a week or so to see if it looks cranky or not.