I have a 99 crew cab 4x4. It had 4.10 gears originally, with 285/75 16 tires. It now has 3.42 gears. Ive had the speedo calibration done at my local dealer by the tech 2. The choice 285 is not there, but we calibrated it for 238/85 16, which should be as tall. How can I go about getting the speedo correct, is there a problem with the gears in the T-case possibly. I also have a CO238 code, which is wheel speed mismatch. HELP please. Thanks