Amsoil has just released a gear oil report they commissioned an independent lab to do for them. You NEED the information in this report
http://www.amsoil.com/lit/g2457.pdf to know which gear oil to use to properly protect your expensive vehicle.
I'll leave you with this; there are several gear oils out there that DO NOT protect anywhere close to the level they need to.
Sure I'd like to sell you gear lube, I'd be almost as happy to hear from you telling me you drained out one of these offending gear lubes and put in a competitors gear lube before you lost your vehicles differential..!!! REALLY