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Ok this might be here some were?
ZD30 GU 3
Fuel catrigde p#1640359EOA (Nissan) $48.73 x1
Oil filter ...

The seal can be replaced with the transfer case in place.
Drain the transfer oil, remove the front driveshaft, remove the front driveshat output flange from the transfer case-you will need a puller...

15w40 should be fine for your climate. Personally I use Caltex Delo 400 15w40 multigrade (don't buy it from a servo, you can get it nearly half the price from places like Independent Fuel Supplies)....

You describe it as a rattle. try to figure out where it is coming from for the purpose of this answer im going to assume top end because if there is somethong wrong with the bottom it a knock not a...