After purchasing my 03 Chevy 2500HD, the main option missing I really wanted was cruise control. I had searched many sites and could not find much information on adding cruise either factory or aftermarket to this truck. Some sites said you had to cut and splice wires, some said aftermarket was the only way, etc. I ended up buying the combo turn / wiper / emergency / cruise switch from an avalanche off e-bay and replaced my non-cruise switch with it. There is one extra 4 wire pigtail on this switch for cruise. My truck had the matching connector taped up under the steering column directly above the tilt lever (inside the housing of course). Making that simple connection to the new switch enabled all cruise control functions. The cruise light on the dash even comes on. All functions to accelerate, decelerate, set, resume, and off work. Brake tap disables as expected. If you don't have cruise and have thought about adding it to your Silverado, check and see if you have the connector for the switch to plug into. From what I have read, 99% of the 03-06 Silverados are wired for Cruise whether they actually have it or not. No reprogramming was needed for this function to work properly. Easy modification and very well worth the time! I bough my switch off ebay and paid right at $50 for it. Good luck everyone!