Hi Guy's, Hoping someone can shed some light on this. I have a 97 Suburban, runs fine, has 211,000 miles on it. When I put it in 4wd high or low it sets off fine but after maybe 30-40ft there is a huge/loud "clunk" that you can feel in the floor. Feels like it is the front left ??? once it has "clunked" i can keep moving and it is fine until about the same distance and then it does it again - etc etc. It is fine when coasting or going backwards in 4x4 but going forwards under load their is this alarming clunk every now and then. I can shift back into 2wd and everything is just fine. Anyone any ideas? Took it to the dealer and got the usual run-around and wanted to charge me $200 to pull the fluid out of the transfer box to see if it had metal in it, I figured I could do that for a quarter of the price - but haven't yet. Any clues, whats it likely to be? Thanks - Chris.