I am planning on changing the differential fluid soon. I know the diffy drain plug gasket can be purchased from Nissan, but I have called several dealers and they do not stock the gasket. It could be ordered for me though. What do they do when they service the differentials themselves. I guess they do not change the gasket. I could not find an aluminum plug gasket in the dimensions needed anywhere else.

I did found a suitable replacement gasket from Napa. The part number is 704-1356. I paid $2 for 2 gaskets. It is a copper gasket, but it is the exact same dimensions of the oem gasket, which is aluminum. I know this because I have a used gasket from another Nissan Frontier XE which has had it's diffy serviced. I would not think it would make any difference on sealing qualities between the copper and aluminum.

I have a XE edition but I think it is the same gasket for both types of differentials on the Frontier. I plan on going back with Mobil 1 75w90.