This is the purple plastic "U" shaped pin-retainer clip that slides into the ECM connectors on the 2006-2010 LBZ/LMM Duramax (also fits the 2006 LLY trucks). It is very common to either lose or break this small clip when disassembling the ECM connectors to install an EFILive DSP-5 switch or high-idle kit. BT DieselWorks has you covered with a genuine Bosch-OEM replacement part. This clip is NOT serviced separately from GM; if you go to the dealer, they will only sell you an entire replacement connector. Why pay the dealer $75+ for the entire connector when all you need is the small plastic clip?
Select which ECM connector you need the retainer for. "C1" is the larger 96-pin ECM connector. The C1 retainer is most likely the one you need!!!