First, thanks for the post. Unfortunately I got information overload from the original post, then I got wore out trying to find answers on 109 pages of follow-on posts. So, I'm sure you've answered this numerous times.
I have a 2018 Sierra SLT 1500 with the 5.3 Flex and with what appears to be the DL3 mirror option. I want to do the DL3 to DQS conversion. I've found the mirrors on-line with GM 84228891 and 84228892. They're around $470 ea plus tax & shipping.
1. Do I need to purchase separate wiring harness or do these just plug and play?
2. Besides GM Parts Direct, are there other options for purchasing the power folding DQS type mirrors?