On my 38 the bed was the same width as the outside edge of the running boards on the truck. Thought it looked fairly balanced about 7ft wide.Another measurement you may want to check is the width between your outside tires as you would want tires completely covered by body width. The hinge mounted mirror arms are available from Jim Carter but they are NOT the correct ones for big trucks. He does offer extentions but they are a bolt on folding extention look a little goofy. My 38 never had a passenger side mirror don't know when they started puting them on 38 litature doesn't show them. Some thing I had never paid any anttention to until one day I pulled out to pass, no window thru grain bed either. I looked at some of the 40's and fiftys era dodge including military they havea hinge mounted mirrors however the hinge mount is not shaped the same and may require longer and threaded hinge bolts to keep mirror arm tight.

Last edited by kb3csw; 12/09/2009 4:09 PM. Reason: thunk me a thought