You might be stuck between Hi and Lo in the differential. You can check if you have vacuum at the differential. If you have vacuum then the diaphram in the power unit could be defective. Remove the power unit and see if you can move the gear with a lever. I was stuck between gears at a major intersection during the summer in Phoenix. I crawled under the truck and used the handle of a hammer to pry the gears into place. This is probably where you need to start. Redcoat
