Today while in 4 wheel hi every once in awhile when I go into reverse I get a grind. In forward no problem. I couldn't shift from to 2 to 4hi without moving which has never happened before. This persisted for about 45 minutes then it cleared up. Is the tolerance so close that if a little bit of snow or ice gets wedged into the linkage that it won't go totally in and why only in reverse. It is a 2005 automatic with 43,000 on it. I've been plowing with it for 3 years and it's the first time this has happened.It is 19 deg out and the JEEP sits outside all winter and only gets driven to plow snow. There is no way to work on it until it warms up.I usually drive in 2 from stop to stop. I only use 4hi to plow unless the roads are really bad.Has anyone else experienced similar problems or have any suggestions?