For the last week or so my truck has had an increasing annoying vibration when accelerating and going down the road at about 70.. I keep checking my u-joints front and rear, my wheel bearings, re-balanced my tires. and still cant seem to locate what the source of this vibration is. So my question is, since my truck is an ext, cab long bed I have 2 rear drive shafts with the center support. Is there some type of bearing or bushing in that center drive shaft support that could be played out after 270,000 miles?

 

yeah ... jack up ur truck ... put it in neutral ... then check the carrier bearings .. also look for missing balance weights too .. that can cause a sudden vibration

 

Also most of the times with u joints they act ok untill you take the straps off and then they fall apart into a pile of burnt grease and needles. But yes their is also a carrier bearing, and the weights on the drive shaft.