i have a 1500 but i just used the permatex for mine i have changed them twice allready. and have not had them leak yet. i do know that you have a diffrent axle though so i dont know about yours. is it just a paper gasket. or is some sort of molded one? if its just paper ona flat surface then the permatex is the way to go. mine was just a flat surface and accully didnt have a gaskit on there from the manufacturer. so if you havent opened it up yet. i would say make sure you have another car to get the gasket if you need to but the permatex is what i would go w/ hole this helps ooh about your question unless it is a o-ring its not reuseable.
All Dodge RAM 2500's & 3500's with the AAM axles do indeed have reusable gaskets on the differentials. Be sure you can easily remove the fill plug before removing the cover bolts. I've already changed mine in my 11.50 AAM rear and the front....it's no big deal. Just make sure you have the proper amount of fluid before starting work. I'd be reluctant to use the Permatex...there's been lots of other owners on the TDR site that have changed their axle fluid out 4 or 5 times and the reusable gasket is still doing its job.