I am looking to buy an 03 Suburban. When testing it out, it clunked when we switched it from 4 high into 4 low and when we took it from 4 low back to 4 high or 2wd. It seemed to drive fine in all modes, but the clunking noise when it changed within the transfer case has me worried. Does anyone know what could cause this? Should I stay away?

 

one mans clunk is another mans clink. mine always clunked to some degree. if you were on the brakes when shifting it tends to clunk more as there is little give. Mine wouldn't clunk so hard if I shifted between the two while my foot was off the brakes.

 

The clunk is pretty much normal Chevy.
Most times it's just when you change from 4lo to 4hi.
You can suppress it some, if you shift into neutral about 5mph, then press the shift button, and when you hear it change, put it in Drive and you're on your way.