Great job Casey!
I will be using your write-up when I finally get around to doing my 2021 GMC Sierra SLE with the IOS stereo (black and grey connectors on stereo control module)
I’m having trouble locating the Axxess harness up here in Canada. I found one on eBay.. and sent a request for a quote for shipping.. no reply
Maybe I’ll stop by an actual stereo shop and ask if they have access to the Metra line of products and see if they can order the harness for me.
I have already replaced the speakers in the pickup, and it’s made the audio tolerable now, but the new speakers are designed to be used with an amp, and are nowhere near as efficient as the originals.
I plan to use the AudioControl D.6-1200 with built in DSP to tune and amplify the audio when I get the harness taken care of. I have zero intention to cut any of the stock factory wires, so I’m willing to wait until I find the correct parts.