Typically my 96 explorer will clank and pop while in 2 wheel drive between
30 and 50 MPH, either at a constant speed within that range or during decceleration. This is not a cyclic or periodic clanking, very sporatic, not to any speed on truck (ie engine speed, wheel speed). I noticed that when I engage it into 4x4H on the roll that it clanking will stop. I have a feeling it is the transfer case drive chain and/or sprockets, maybe slack in chain causing the popping, but am not really sure. I can not get a solid answer out of anyone. I do have a strong feeling that it is definitely something to do with the 4 wheel drive. Anyone have an answer???