There is a little plug on the side.  Clean it, open it and stick you
finger just inside.  If you feel oil, the level is good.  The recomned
oil is hypoid gear lube, SAE90.  If you see no leaks, your not likely to
be missing any, unless the seal to your tranny is bad, then the gear oil
goes to the tranny which give it a more yellowish colur.

--
���� �ϼ���, (Work hard, but don't kill yourself at it) [Korean Proverb]

Tim