I posted this thread earlier trying to find the cause of a huming sound at idle... Anyway, right now I'm under my truck trying to look at anything that may be the cause of it. I just noticed that there is a rubber boot around the driveshaft about 2/3 down the shaft. What exactly is that boot covering?? The reason I ask is because the boot has a RIP in it about 2" long. I'm wondering if that could be making the unwanted sound. Thanks...

 

In case I didn't accurately describe the rubber boot that I'm talking about, here are a few pics...

 

If I'm not mistaken, I believe that is a two-piece driveshaft.

-Travis

 

yes the driveshaft has a carrier bearing, but it's about 10 inches from the rubber boot

 

So then what's the rubber boot for???

 

???? i'd like 2 know as well

 

It is a dust cover for the splines.
The driveshaft is splined so it can get longer or shorter when the rear end moves up and down,since you have a two piece driveshaft it can no loner use the transmission splines therefor they and spline into mthe driveshafts. Simple geometery will help you to understand better.
But this would not cause a noise when at a complete stop since your driveshaft is not moving. Unless you are getting 100 mph wind under your truck everytime you stop. I would get the boot replaced eventually, but it wouldn't kill your truck to leave it like that for a little while. unless you are planing to do some offroading.