I have a GM 10-bolt now residing under my car. I don't even know how many times removed from the original it is, but it replaced a 9-bolt that just didn't want to hold my 3.73's. My question is...where is the gear oil check/fill hole? I noticed I have a plastic tube-type-cap at the passenger top side that's kind of snugged in. It comes out with little force and a finger-twist...is this it? Also, the mechanic moted on my bill he put in 2 1/2 quarts of synthetic gear oil...is that the correct amount? I thought it was s'posed to be closer to 3 or 3 1/2?

I hope it's low cause that bee-otch is loud!
Thanks guys....
Eric

A rubber plug on a 10 bolt? The rubber plug is only in the cover of a 9 bolt. The 10 bolt has a metal fill plug on the passenger side of the housing in front of the axle tube.

2 to 2-1/2 is fine. They don't hold a lot of oil. I'm surprised he was able to get 2-1/2 in there.

I would think that could be the axle vent cap.

OK cool, I saw that plug on the pass side of the housing. Didn't know there was a vent cap..but i do now. Thank you both for the assistance.

Eric