im gonna break open my rear diff tomorrow and clean it out real good and replace it with amsoil rear end oil, and i wanna do a gasket istead of sealer, so which would be the best gasket?? wix probably??

 

dude, a gasket is unnecessary, and will only make more of a mess to clean the next time the differential is opened. ford doesn't use one, and the differentials don't leak from the factory... however, if you are insistent on using one, get felpro.