Yes Lube Lockers work great unless its seating surface is flawed where they don't do so well. My Rubicon's rear Dana 44 seals fine with a Lube Locker but not the front axle that I spent a lot of time on trying to get the Lube Locker to seal it too. I ended up sealing that axle with RTV, I gave up on the Lube Locker. Its seating surface looked to have to flaws the Lube Locker couldn't cope with.
GL-5 for sure, pretty much any viscosity from 70W-80 up will be fine. I do recommend a conventional GL-5 gear lube after I learned my new gears ran too hot with a synthetic GL-5. It was discovered by aftermarket gear & axle manufacturers that new gears do run significantly hotter with synthetics. Your gears aren't new so you wouldn't have that issue with them but they'd still run cooler with a conventional. Personally I run Valvoline but any good brand like Torco, Castrol, Mobil, etc.
P.S. Both Revolution Gear and Currie instruct to use only conventional gear lubes.