The issue I am having is my speedometer is reading 30 to 40 mph fast. The speedometer says 100 mph and my gps says 65, speedometer says 55 mph and gps says 30 mph etc. The speedometer starts off at zero and operates as it should just reads entirely too fast. The truck is all original and bone stock. Original drive train and original tire size with no customizations. Any advice would be greatly appreciated.

 

This issue is often caused by a bad vehicle speed sensor or a problem with the instrument cluster. Since your truck is stock with the right tire size, gearing should not be the cause. I would start by checking the vehicle speed sensor on the transmission and the wiring to it. If the sensor and wiring are good, then the problem may be inside the cluster itself, and it may need repair or replacement.