This is a used Jet Performance Module for a Chevy/GMC truck with the 5.3 Liter engine. It is the Stage 2 Computer Module. I had this module in my 2005 Silverado 1500 5.3L and removed it before i sold it. The module is plug in and play, no messing with anything else. It can be used on more than one truck, and there is NO VIN learned to the module like a Hypertech module. It increased my fuel mileage by 1 mpg, and my horsepower went up 6 at the rear wheels. I no longer have the dyno sheets because they were in the truck when i sold it. This is a perfectly good, working condition module. No Damage. Back in it's original box and ready to be installed again. It installs between your trucks PCM and the large connector. It's located under the hood, down by the frame rail on the driver's side. They do sell for over $200 new, so happy bidding.