this morning i when i put my dmax in reverse to leave for work i heard a clunk, thought nothing of it. had to put in in 4wd to get out of my drive way and then put it back in 2wd when i got goin. i head some hum/vibration and thought maybe it was just still stuck in 4wd. the vibration is gettin worse and i know its not still in 4wd b/c only the rears were spinning when i got on the snow at work. I think its the universal joints b/c of the clunk goin into drive and reverse and vibration, i havnt got under the truck yet b/c its 0 degrees out. any one have any other ideas of what it might be? or could i actually be right and have a bad u joint?