Question about speed sensor and it\'s effect on shifting/tcc lock up I have an 88 k5 with 1ton front and rear (off a 74 p/u) They are geared at 4.11 and I have a stock 700r4. I'm running 35"ssr's so the speedometer is quite a bit off. While using the "SCAN TOOL" the other day I noticed that It reads the same value on the speedometer on the scanner when in motion. I initally thought that in 1988 the speedometers were driven mechanically and the computer could not take a reading of the speed. My question is... Does the fact that the speed sensor is reading a false speed affect the way my truck is shifting, and if so, How can I correct it? Tha truck seems a little sluggish, maybe due to lock up happening in the torque converter too soon???... Please help!!!