Well, I decided to only replace the driver’s side since that controls air flow and see what happens, $50 including tax and shipping from Rock Auto. Got it in two days with the cheapest shipping ! If it didn’t fix the problem, no big loss plus a commonly failing part had been replaced with a better one. It came today and my curiosity was killing me, so I got right to it. Many report doing it in 30 minutes but it took me an hour. Old, clumsy, not much room, lol. One thing I noticed is that if you could remove the air bag panel, this would take 5 minutes but I was reluctant to try that, not knowing what the consequences might be or how to do it safely. One tip I did not see in the videos I watched is that you should pay attention to the orientation as it sits in the car before removing it as the new unit is not shaped the same as the old one and it has multiple superfluous screw holes that can be confusing when you go to put the new one in. In any case, my AC vents now work perfectly. I am so angry. The dealer “diagnosed” a faulty evaporator housing (the PN they gave is an assembly and includes a new evaporator). Quoted list, of course, $1462, including tax. Then 12 hours labor @ ONE HUNDRED EIGHTY DOLLARS AN HOUR ! $3,622 total. 4 days in the shop ! Complete removal of the dash (how many squeaks and rattles would THAT cause ???). I do NOT believe this was incompetence on the part of the dealer. I think this is intentional gouging, blatant profiteering. I hope to find both the General Manager and the Service Manager at the dealer tomorrow. I have an ‘18 Raptor, a ‘16 GT350 and now the ST. It will be a long, cold day in hell before they ever see me again. Too bad, because I live in a small city and the next nearest dealer is over 100 miles away (Vegas) and I’ve tried buying cars from them and they were sleazy with outrageous ADM’s. Phoenix has multiple dealers to choose from, so I guess I’ll go there but that’s 400 miles, round trip. Thanks to all who’ve posted useful hints; the most useful was the video on page 2 of the “All Encompassing ……..” thread. It walks you through the whole thing. There’s another video on replacing the passenger side, I believe it is on the same page. Driver’s side is awkward, no question, but it’s not hard, just be patient getting it mounted correctly.