My husband has a much-loved 65 Fleetside which he drives every day. We replaced the six with a V-8 crate motor since we often tow our race car. The problem now is the stumpy rear & that tractor 3 speed. Awful gas mileage & it's in top gear at 30mph. Does anyone know of a taller rear that will fit? Any ideas for a floor mount 4 speed? Thanks, Sue