A little bit of succession replacing the mirrors with DL3's. I also stumbled upon some useful information that will help future owners wanting to upgrade to power folding mirrors. The mirrors I got were busted. Both motors turned, but didn't fold the mirrors. I installed the two motors I got from Amazon
https://m.media-amazon.com/images/I/61m7NaJZCkL._SL1500_.jpg
Now everything's folds as it should. So you do need. to have both switches and the mirrors. My Suburban is a 2007, first year of the GMT900, and even thought the mirrors fold when I hit the switch, I don't have the ability to fold on lock by holding the lock button on the remote a few seconds longer like on my 2016 Sierra. I am not sure if this feature was added to later Tahoes & Suburbans. No extra options were added to the driver information controls. I am wondering if this was an option on later vehicles. If anyone have any ideas, Please chime in. Also aftermarket power mirrors will work, you dont have to look for DL3 mirrors. You only need to have the switches. I confirmed this by plugging my aftermarket mirrors in, and they folded as well when I hit the switch.
https://photos.app.goo.gl/SaRcUNSJvX8gaXnD6