This E.C.M. fits the following vehicles: 2010-13 4.8/5.3/6.0/6.2L Chevrolet Silverado (1500, 2500HD, 3500HD). This is for one service number 12633238 ECM (Engine control module) that is programmed for your vehicle using the la software updates using your V.I.N. (Vehicle identification number) to exactly match your vehicle. After you purchase the E.C.M. you will need to provide us with your V.I.N so that we can program the E.C.M. E.C.M.The vehicle may or may not start once the computer is installed. If the vehicle does not start an antitheft password relearn procedure will have to be done. Also, the vehicle may run for a period of time (weeks or months) and then will not start and may set a code P0633. If this occurs the following procedure will have to be done so that the security password will be learned by the replacement ECM. To avoid any inconvenience it is best to do this procedure at the time that you install the replacement ECM. This requires a programming tool (J2534 interface tool or equivalent) and a subscription to (cost to program one vehicle is $40.00) A properly equipped auto repair shop, dealer or locksmith can do this procedure. A crankshaft variation relearn will need to be performed once the vehicle is running. This will be evident if the check engine or service engine soon light comes on once the vehicle is running. You will need access to a scan tool capable of doing this procedure to do this and clear any related trouble codes (Code P0315). If this is not available to you a repair shop will have to perform this and clear the related trouble code. The vehicle will run normal but the ”service engine soon” light may come on and a trouble code will be stored until this is resolved. . Same day ping if ordered before 2:00 EST (Mon-Fri)