First the main board must be removed from the 1227747 or 1228746 ECM:


WARNING: Remove the main board from the ECM ONLY on an anti-static surface or the internal components may be damaged by electrostatic discharge!



Then the factory connector must be removed from the main board by de-soldering the pins.



A word of caution: If you are not experienced or comfortable with de-soldering methods then you should NOT attempt to remove the factory connector!   The main board may be easily damaged by improper de-soldering methods.  An installation service will be available for those that are not comfortable with de-soldering or do not have access to someone qualified to remove the factory connector.


The Adapter is then mounted in place to the two tabs (that GM was nice enough to provide) using two 6-32 screws and two #6 x 1/4" spacers:

The two mounting tabs will be un-threaded.  Using a self-tapping steel 6-32 screw or a 6-32 tap will easily thread the mounting tabs. 

Tip: Since the adapter is mounted from the bottom side of the tabs, the easiest way to mount the adapter board is by using a 6-32 hex-head capscrew and a small wrench.  Otherwise the main board must be totally separated from the ECM chassis rails in order to get a screwdriver to the adapter mounting screws (which means disassembling the injector drivers from the heat-sink).