I have a 2002 4X4 Quad 3.9L 5 speed manual. Every now and then there is a snapping popping sound from under the driver seat area (can also feel it in the floor boards and shifter). This occurs for several miles then goes away for 300 - 400 miles of trouble free driving. In 4WD high though the popping snaping is much more frequent. Dealer gave drive shafts and u joints a clean bill of health. They couldn't replicate the problem. Wouldn't pull x-fer case due to $$. I have 80K miles and only use 4X4 ib snow. The x-fer case seal says New Process Gear model 233D. Anyone else have this sound.