The Lube for front and rear differentials

Hi, Everyone -- I'm draining my differentials on my 1966 CJ5 (first time; actually removed the cover to pull out the sludge), and the Fac. Service Manual states that the lube to use is MIL-L-2015b @ SAE 80. Well, I don't see any info (googling) on that specific gear lube. Information comes up about MIL and GL-5, etc., but nothing on the 1966 FSM specs for lube.

So, I'm wondering what some of you use. I'm thinking to NOT use any lube labeled GL-5 (because of corrosive qualities), but is it okay to put in 2.5 pints of plain old Valvoline (or equivalent name brand) gear lube that is SAE 80. And should it be rated GL-4, or is the GL-4 rating not important for differentials? -- thank you, ronnie

 

GL4 is important for the trans, but not the diffs.
Just use regular 80W90 gear oil.
Use limited slip additive if so equipped.

 

x2. The GL-5 issue is primarily with transmissions and the blocking rings. No such problem in the differentials or transfer cases on these Jeeps.

 

Walmart 85W90 gear oil in the gallon jug ... add friction modifier if you have limited slip.