all I run in my rear diff is Lucas 75-140... mixing it wont hurt a thing... save the PITA and the cash

 

I agree, the mix won't hurt anything. The G80s problems are purely design and use related not oil related.

 

My truck has a tranny and rear diff drain plug.

 

The diffs only had plugs from 99-02, not sure about the tranny.

 

Ive had 4 different 99-02 rears.... none with plugs....

 

WOW???

Did they at least have the pad where the hole is normally?

wtf

 

nope, identical cover to the 03 Z71 rear thats in the truck right now.... its a 2000 2wd BTW

 

Weird, both my stock rear end had one, and the one I picked up in a junk yard did too.

Both 3.42 2wd with disk brakes.

 

You mean the square head plug on the bottom of the differential housing itself right?


If he does, then your cover shouldn't have a hole, the axle should LOL!



BTW, mine does. But I haven't been able to use it with my new diff yet, I changed the fluid and the cover gasket after break-in without even realizing the plug was there. And then, the next time I had to change it, two weeks ago now, my diff cover gasket had a leak, so I couldn't use it again. At least I have a truck built BEFORE GM started cutting costs so much that a $5 drain plug was a serious issue.

 

yeah, the plug is on the underside of the pumpkin. It's kinda hard to see unless you really look for it.