You could try California push pull inc.. they make custom cables.. I picked this tip up here.. by some great members.. also you can go to AutoZone. Com.. don't enter rv.. use Ford 2000 f350 with same eng and trans.. many Ford pickup parts fit rv.. if not.. they will take back.. I get p# 905-615 Dorman shift cable there are others listed.. or try 2000 f450.. you will see what they are.. you just got to get a little creative..
Good luck and keep us posted
2000 southwind storm, workhorse custom chassis with 7.4l vortec