Is it as simple as pulling out the plug and the fluid should be up to the bottom of the hole?

 

Yes.

 

Yup, that's all it is. If there isn't, you can gauge how far down it is with a section of bent wire to act as a make-shift dip stick. This will at least keep you from running oil all over the place if you just go crazy topping it off.

 

So is there not a drain plug on a 1996? That's what I think I'm hearing...and if there isn't..how do I drain it? I don't have any pump.

 

From what I remember most GM diffs don't have a drain plug since fluids are supposed to be sealed they don't need replacing as frequently as motor oil, they also don't get as hot as engine oil so they don't break down. So any drain plug found in a cover may be an aftermarket cover.

So to completely drain a diff you have to loosen the cover bolts enough to break the gasket seal and woila instant drain...this design has worked for many decades...

 

Well, speaking of rear diffs, yeah, you have to pull the cover. I have never seen it, but word is that some of the IFS diffs didn't have a drain plug and to open the case on one of them would be a major PAIN...

 

I always use my pinky...for checking anyways...the fluid should be up to your first knuckle when sticking your finger in the top

 

Both of the diffs on my '00 have drain plugs.

 

The ZR2 is a different rear (8.625") than the rest of us have. It is possible that they also added a different cover to the rear axle.

 

Yeah, I know... the drain's actually in the casting, the drain is on the front of the diff, not on the cover.