I recently put a set of 4.56 gears in my 96 2500 V 10. I have a speedometer calibrator and before I calibrated it when I was on the interstate and was going 75 mph my speedo said I was going 95 mph. When I tried to set my cruise control it would drop me down to 93 mph automatically. After I had calibrated the speedo I tried again to set my speedo for about 77 mph and once again it dropped the speed down to 73. Below 73 however, it stays at exactly what I set it at. I assume it's a safety feature but is there any way to get around that? I need help this is extremely annoying!