Welcome to the club Will.
Sounds like you need to replace the oil seal on the back of the gearbox/transferbox, if you have oil leaking out.
1. Mark with a pen across the drive shaft flange onto the flange its bolted on to, so you can bolt it back on in the same position.
2. Unbolt the drive shaft, just on the gearbox/transferbox end and pull it off the studs, you may need to give the flange a tap with a hammer and prise between the flanges with an old screw drveir if its tight.
3. Remove the big nut holding the flange onto the back of the gearbox/transfercase, and remove the flange.
4. Pull out the old seal using a small screwdriver/needle nose pliers.
5. Carefully tap in a new genuine Toyota seal using a soft faced mallet (nylon/cowhide), working your way round bit by bit.
The grease nipple is just for the Universal Joint on the drive shaft and you should give it a few pumps of grease periodically to prolong the life of the joint.
