My automatic transmission won't go into reverse and it doesn't want to shift into 4Low very easily. When I realized I couldn't get it into reverse we tried to push it backwards in neutral but after about 4 feet it wouldn't move anymore. Any ideas? All I know is that the 4wd is engaged by vacuum but I don't know if that would have anything to do with reverse. I was stuck in the mud last night when it happend, I'm just hoping that it won't be as bad as it sounds but it probably is.