gistfile1.cs

            routes.MapRoute(
                name: "Mount",
                url: "HitchLookup/Mount/{mount}",
                defaults: new { controller = "HitchLookup", action = "Mount", mount = "" }
            );

            routes.MapRoute(
                name: "Year",
                url: "HitchLookup/Mount/{mount}/Year/{year}",
                defaults: new { controller = "HitchLookup", action = "Year", year = "", mount = "" }
            );

            routes.MapRoute(
                name: "Make",
                url: "HitchLookup/Mount/{mount}/Year/{year}/Make/{make}",
                defaults: new { controller = "HitchLookup", action = "Make", year = "", make = "", mount = "" }
            );

            routes.MapRoute(
                name: "Model",
                url: "HitchLookup/Mount/{mount}/Year/{year}/Make/{make}/Model/{model}",
                defaults: new { controller = "HitchLookup", action = "Model", year = "", make = "", model = "", mount = "" }
            );