This E.C.M. fits the following: 2007 4.8/5.3/6.0/6.2L  Chevrolet Silverado (1500, 2500HD, 3500HD)This listing is for one service number 12597121 ECM (Engine control module) that is programmed to 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. before we ship it to you.This computer is refurbished and tested for functionality.There is no core charge you keep your old E.C.M. There is a one year replacement warranty.We will include instructions for the 30 minute security password relearn procedure which will need to be done before the vehicle will start.  This is a "do it yourself" procedure that requires either a battery charger be connected to the vehicle or jumper cables be connected to another vehicle that should be left running the whole time.  On some vehicles this procedure may not work, if that is the case refer to the paragraph below.****This computer may require a theft deterrent relearn that must be performed with a  programming scan tool through an online subscription with ACDelcoTDS before it will start the vehicle.   A dealer or properly equipped repair shop can do this (charges will vary).****A crankshaft variation relearn will need to be performed once the vehicle isrunning. 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 will come on and a trouble code will be stored until this is resolved.We will ship within one business day of payment.Same day shipping if ordered before 2:00 P.M. EST (Mon-Fri)Flashmasters does not use ACDelco Technical Delivery System (TD