I have a 1999 Trooper 3.5 Six with a 5 speed manual and manual Aisin hubs. I am having problems with the 4 WD. When I engage the 4X4 dash switch in 4 WD High, it constantly jumps out of gear. However I have no problems with this jumping out of gear when it is in 4 WD low. The 4X4 has not been used that much. I am wondering if anybody else out there has had similar problems, and what might be the cause as well as what did they do to correct the problem. All replies requested and welcomed.