2002 GMC 2500HD 4x4
6.0 gasser / 4L80E
10.5" 14bt FF rear axle
NP263 T-case (push-button)


Changed my fluids in front and rear diff last night to Mobil1 75W90 synthetic. The rear axle has the drain plug on the bottom and the fill plug on the right side of the carrier, just behind the pinion - same way my Z-71 was - not on the coverplate as most of you have. When I filled it, it only held about 2.5 quarts before running out of the hole. That sound right? I haven't seen anyone with a 10.5" talk about changing fluid on here before - most of you guys have the 11.5".

Front held 2 quarts. Going out to change the T-case fluid right now to Mobil1 synthetic DEX-III. Oh, yeah and to get back under and hit that 11th zerk on the pitman arm that I forgot last night. :cool:

I just did mine today older one though and it took almost 3 bottles of Mobil 1 gear oil

I have the same axle and mine took just about 2.5 also, maybe a little bit more.

http://mysite.verizon.net/vze7z5f3/sitebuildercontent/sitebuilderpictures/reardiffdrain.jpg

Yeah, someone over on GM-trucks.com told me the spec was around 2.7qts. Thanks for the follow up though.

Does yours have a magnetic drain plug? Mine doesn't.

No, mine didn't either. It kinda looked like one, but it wasn't. Sooner or later I may get the Mag-Hytec cover. Much more capacity and a magnet.

I wonder if the magnetic drain plug from the 11.5" rear would work on the 10.5"?

The good thing about this type of fill is, your question is redundant! when the oil flows out of the fill hole, it's full... Mine took 4 qts (but it's an 11.5) and it when it was full, well I stopped trying to put more in! ;)

Not trying to sound like a smarta$$ here, but you should read about the Ford 6.0 diesel owners "guessing" on how much motor oil to put in... :D Differentials are, well, different... :)