Yes. Take the driveshaft and slip it on the rear output shaft, and turn it by hand to see if the gears work ok, smooth, no binding. Drain the lube, letting the draining lube juice run over a magnet, and check for lots of metal. Minor fine metal power (too fine to feel any grain) is probably ok. Move the h/l shifter fork (the one on the right, I think) to engage low range, and check for about 2:1 diff in input and output rotation speeds. Engage the 4wd shift fork and make sure the front output shaft turns with the rear output at the same rate. Try to move the output shafts and input shaft axially (fore and aft) to check for bearing wear. Should get no movement. Replace output shaft seals.