I have a 194 Silverado C1500. The speedometer jumps all over the place. I have changed the speed sensor a the plug to the sensor, the speedometer cluster and the VSSB. I also checked the wiring to the speed sensor in the transmission using a volt meter,(it checked good, and output increased as I throttle). I did notice that the VSSB only had one plug going to it. The VSSB was used and so was the speedometer. It shifts fine from 1/2 but sporadic shifts from 3 to overdrive. Any help would be appreciated