Hey, have you actually looked to see where he said it was leaking at? The diff can be leaking from the cover. Which you could pull, clean, rtv and then install. If it's leaking from where the drive shaft enters the axle then it is your pinion seal. Which you have to pull the drive shaft, the yoke ( has a one time use nut but some people locktite the crap out of it and torque it to I believe 160 in lbs). Then the seal you just beat the edges out with a hammer and chisel. The new one you hammer in but be gentle and use a piece of wood or something to hit against, or you will damage the seal. I've never had a transfer case leak so I cant help you there! O btw you won't really see any fluid from the rear diff. Its very thick and probably won't be leaking bad enough to drip to the ground.