You only need to worry about overfill if you are filling from another hole besides the one I mentioned above (I.E: a fillhole on an aftermarket diff cover). If you are filling through the stock hole, just fill until it spills out, and that's the perfect level.

 

Cool.

Last question... I used alot of the gasket stuff... It 'spilled' over the sides when I tightened the cover... Which means it 'spilled' over on the inside too. Is this dangerous to the axle if it mixes with the fluid? Just curious... I mean I didnt use an insane amount but definately more than was originally on there.

 

The minute amount wont cause a problem. The ring/pinion will act like a grinder and it will disolve.

 

By the way... the old fluid was pitch black with of course glittery metal speckles. The Mobil 1 I put in was light tan, just like motor oil.

Is it normal for some gear oils to be pitch black?

 

Well...

Took a drive. And wow, it shifts smooooth. Why would a differential affect shifting? I drive a 5spd by the way. Weird... I only changed it because of break-in, I really don't plan on servicing it for like 50K miles. But to my pleasent surprise it seems to shift considerably better.