||05-11-2009 03:34 PM
Yes, you can use the same weight front and rear. And unless your rear axle has a Tracloc limited slip differential, you don't need the friction modifier limited slip additive. The front axle definitely will not. As an aside, most off-the-shelf gear lubes suitable for axles already contain the additive anyway so it's usually not necessary to add the additive separately when you do have the Tracloc LSD.
Go for a good brand of GL-5 gear lube, the viscosity is not critical. 70W-80, 75W-90, etc. is fine. Personally, I prefer a non-synthetic gear lube for my axles because recent tests by some axle manufacturers like Currie have found that the gears inside typically run cooler in a non-synthetic gear lube. :)