Okay I have a problem with my 4WD...recently I have been getting loud clunking noises eveytime I have my truck in auto4WD, or in either 4-hi, or 4-lo. I think it is coming from the transfer case...it happens eveytime I get on the gas a little bit, then CLUNK, and the whole truck shakes...is my t-case slipping, or is it in the front diff? Any advise would be good...thanks.