I was just going through some notes of mine, and came across some transfer case and transmission oil specs, and thought I would post up. I had a little difficulty finding this out for myself when I was going to do a fluid change, and just figured someone could benefit through a search with this.
Manual Transmission FS5W71C: 5-1/4 US Qts, plus optional 1/2-1 quart (below).
Transfer Case TX-10: 2-3/8 US Qts
When adding fluid to the transmission, I poured into the shifter hole (which can be accessed by removing the shifter [remove boot, splash guard, shifter grommet, and snap ring, lift shifter from transmission]) and added an extra 3/4 quart of oil to make sure the transmission had enough to lubricate the main shaft bearing set in the adapter plate, and the front main transmission bearing which was what actually failed before I rebuilt the transmission. The transfer case is very difficult to access and fill, an extra set of hands, a funnel, and a rubber tube is necessary. To remove fill/drain plugs on the transmission and transfer case, a 1/2" drive breaker bar can be used, and an extension is helpful on the transfer case. Be sure to return the drain plug with the magnet on the bottom of both cases. Transmission oils must be GL-4, and are very difficult to find at parts stores (in any viscosity). When I replaced my clutch 10k miles ago, I had to drive 2 hours to find a GL-4 in as thin viscosity as I could find, alas, I had to go with 85w90, which was a bit thicker than what I had in mind. When I rebuild the transmission, I went with RedLine MT-90 which is a full-synthetic 75w-90 GL-4, safe for use in Nissan transmissions. A good rule of thumb is, keep the same oil in your transfer case as is in your transmission, reason being, if the seal between the transfer case and the transmission goes out, transmission oil or ATF in the transfer case will not cause harm, however, transmission oil mixing with ATF or a GL-5 transfer case oil in the transmission can breakdown the brass synchros and be disastrous in an automatic transmission. Fill the transfer case till oil begins to come back out of the fill hole (which should be right at that 2-3/8 quarts measurement).
So, breaking that down a little, use a 75w-90 (or close) GL-4 to preserve synchros. Do not use a gear oil if there is GL-5 written ANYWHERE on the bottle.
Redline is available on Ebay and at SummitRacing.com, not to mention other dealers, perhaps local to your area. These specs are for the FS5W71C transmission which is found in most 86.5-97 Hardbody, which I believe the internals to be all the same. You may see them (rebuild kits) listed in separate year brackets, but the internals (synchros, bearings) are the same AFAIK. The above worked for a 1995 Hardbody 4x4, 2.4L 4-cyl, non-z.