This may have come up before, so excuse the lazyness for not doing a search. As I was changing out the 34 tear old brake lines and rubber flex lines (rears were completely swelled shut), I noticed that the reduction gear boxes have a drain and fill plug. I opened the fill plug to check for fluid. The gears have oil on them (from rolling the car back and forth in the garage), but I cannot make out the level. Do you fill these to the top (doesn't sound right), or just put in a certain amount?
It smells like 80/90 weight oil. Is this what's used?