thats funny mine just started making a noise too. i thought the transmission was going out because it would only do it in 5th gear. when it started doing it the other day i pushed in the clutch, and put the transmission in neutral....still got the noise. now i have no clue. its kind of a banging noise. it seems to go away under 40 mph, and is intermittant above 40 mph. i just checked my spring and it is still there. but if im under the truck with the parking brake off and twist the driveshaft back and fourth it kinda makes the same noise just quieter. this seemed to happen right after i changed my front axle seals, and boots. thats a pretty straight forward job though. i dont think i messed anything up.