I've never seen one that I could confirm was original because I have not seen one in any books. However one book states "A selection of rear view mirrors and brackets to replace or add to the standard equipment supplied, providing rear vision under most situations." but only shows a right side exterior mirror and an extended exterior mirror. That still suggests there might be some types not shown. Since the rear window is often blocked in trucks, I guess it might not have originally been that useful. Interestingly, passenger cars of that era only came with an inside mirror as standard.
