HELP replaced ring n pinion, no other changes . original 10x41 tooth (4.10 ) with 11x45 tooth (4.09) NAPA / RICHMOND GEAR part listed as 4.10 ratio . I had a 2mph difference before and now have 14 mph difference , 74 on speedo / 60 on gps . Replaced speed sensor and still have same numbers . 1998 chev c3500 dually 7.4 auto trans Any ideas