Chevrolet Repair: grinding in 4wheel drive, universal joints, drive noise

Question
i have a grinding noise clicking noise when the wheels spin in 4 wheel drive have 1998 gm 1500 with electonic 4 wheel drive was going into 4 wheel can feel 4 wheel locking but seem be getting progressively worse only seem to have rear wheel drive noise seems to come from transfer case this is the first 4wd i have owned thanks

Answer
First thing to check is your universal joints at the wheels and at the transfer case and differential.  It sounds like your transfer case chain might be slipping.  If you put the brakes on hard in drive and accelerate a bit and hear that noise its the chain.

Wayne