I wanna share my experience with Phil here. Just yesterday I met up with Phil at his place to upgrade my mirrors from DL8 to DL3. Let me say this first, wow! Phil really knows what he's doing and makes it look so easy. I think changing the mirrors took us 45 minutes to an hour to do for both sides. So far Ive been loving them and couldn't ask for any better version of tech support if something goes wrong.
Just a side note, we also added a headlight harness with resistors and added the wiring for the auto-dim rearview mirror. All in all maybe 2-2.5 hours. Absolutely amazing what Phil has been able to make these trucks do when GM tells us no.
Thanks Phil!!