For the past few days have had a rubbing sort of noise noticiable in the cabin from under the truck. Only happens when car is moving, doesn't seem to vary with speed, braking or turning, although it is not immediate when taking off from a dead stop (takes a few seconds, till you get above a crawl speed, then stays pretty consistent). I can't really pinpoint where it might be coming from...thinking maybe driveshaft, differential, wheels...can't really say. Almost sounds like a brake pad stuck and rubbing, but its not - definately not a grinding or squealing sound (yet), 'rubbing' is the closest description I can come up with. Any ideas of where to look/what it might be?