1997 xj transfer case whine

Hey, I got a 1997 XJ with the np231 and 5 speed. Ive owned the car, with 179,xxx miles for about 2 weeks. Ive put almost 800 miles it. I drove about an hour today, and the last few miles a noise developed from the tranny/transfer case area, below the shifter. Its a high pitched whine, that increases in tone depending on engine speed. Coasting it goes away. If I leave it in neutral while at a stop it makes a marbly noise. I crawled under and it seems like its more on the transfer case end. I shifted through all gears and transfercase ranges, and it whines in each. I had to be back on my ship at 11pm tonight not long after the noise developed, so I didnt have a chance to wait for the case to cool down and check the fluid, but I checked it when I first got it (2 weeks ago) and it was fine.

Anyone have any ideas?