ok, before we go any further, you haven't told me if you checked the level and condition of the gear oil within the case???? for example, if it is low, you may want to drain and replace it. when you pull the plug you may find metal debris which may indicate internal damage. I don't think internal damage is the issue as long as you didn't experience loud grinding or popping from that area of the truck. if it is low on gear oil, I would fill it to specified lever first to see if that solves the problem. remove the t-case skid plate and look for a 15/16" plug half way up the case facing the rear of the truck on the driver side of the case. that is your fill plug. the level of gear oil inside the case should be right in line with the bottom of that hole in the t-case, if oil doesn't seep out when you remove the plug on level ground, then fill it until it seeps out slowly. then it is filled to proper level. you must check the gear oil lever first b/c wiring or switches could be just fine the way they are.