Hey everyone, I know this thread has been dead for a few months but I have some info to add that might be helpful for anyone trying to work with this.
Here is an upfitter link on this exact approach: GM Upffiter Bulliten #115C
It says you can order this part from the dealer as mentioned earlier in the thread which makes me wonder why this would void the warranty. What should void warranties is splicing into harnesses etc, not buying an oem connector for up-fitment purposes.
Also, you can order these parts far cheaper from Terminals & Connectors. They supply the plug, the blue latch and the pins. You just need to supply the wiring.