When I'm rolling slowly down a hill in neutral, I can hear a clunking noise coming from below the truck. It sounds like it may be coming from behind the cab, but I can feel it lightly under my feet through the floor pan. The noise is steady, and steadily gets faster as it rolls faster. I can't tell if it makes the same noise when in gear - the noise of the engine drowns out the clunking.

Any ideas what this is and how to fix it? U joint maybe? Thanks.

 

Check all u-joints, motor/trans mounts, etc. If all of those appear ok, check for slop on the pinions on both axles. If those seem ok, drop the rear driveshaft, pull the tailhousing off the t-case, and make sure the snap-ring is still there. (on the shaft, right up against the rear bearing.)

 

Would I have problems engaging the 4 wheel drive if that snap ring wasn't there?

 

Are you sure your spare tire is tight? I know it sounds funny, but that thing can make it sound like a mechnical problem when all it really is just the spare bouncing around.

 

Yeah the spare is tight. I just put new tires on actually, including the spare.

It's a very steady clunking. Not random at all. Starts off slow as the truck starts rolling and as you pick up speed so does the noise - until road noise and RPM's drown it out. I'm gonna look into HeyYou's recommendations when I have time (work is nuts right now) and I'll report back what I find. I was just wondering if anyone experienced something similar and isolated the issue.