I just changed the fluid in my axle, the shop manual calls for a gl-4 hypoid gear oil. Most places sell gl-5 gear oil. I read on the "internet" that GL-5 uses more additives and could attack brass if there is any in the axle. Don't know if thats true so to be safe I just ordered what the shop manual called for. The only place I could find GL-4 was napa.
http://www.napaonline.com/Catalog/Ca...229_0006410049 Or you could use synthetic gear oil, but I am not sure which one to get.