I had the same thought about the ice, but as far as I know all the ice was gone from the truck. My other thought was that maybe since the overpass curves, somehow my 4wd lever may have gotten pulled a little and popped part way into 4wd for a moment when I went over the first bump and popped back on the second bump (no body lift or anything so I am not sure that is possible). I would pull the lever while moving to see if I can recreate the noise, but my Trooper preservation instinct kicks in and I can't bring myself to subject it to abuse that is not in the name of fun. I have found a better price on a new set of hubs, and I agree it is a good idea, but getting the finances approved by the wife can be difficult. Actually from what I can tell, the hubs will engage just by applying power to the front end. I could get them to engage by turning the front driveline by hand with the t-case in 2wd.