CRApex

Fact, I disagree with most of what you've said.

That is a bummer for sure but unfortunately happens. Hopefully they can remedy quickly. I don't think anyone would be happy with that happening on a new vehicle regardless of the selling price.

I think your tire size choice will look too small with it leveled. IMO

L8T not immune from issues. BOTH of our 2020 6.6 gas trucks were down, one for 2weeks and the other for 3 waiting for parts. It happens. My Duramax also had the Def heater issue last year and was down 2 weeks, no issues since.

Here you go..

I'll take a pic today.

I doubt a 30" will fit unless you can find an extra slim light. The issue is they get too tight towards the louvers (if your truck has them). I have a 20", 2-6" and 2 slim 10" behind my High Country grille.

Definately been tough getting parts for virtually anything this past year and its not just GM. Almost every sector and manufacturer is dealing with this.

I have 2 sets of A/M 20" wheels. First set is 20x9 +18 with 295/65/20, they fit with no mods on stock suspension. I also have a chrome set for summer, 20x9 +10 with 295/65/20 Nitto G2's. The +10's needed the front of the fender liner pulled back just a bit (took 5 minutes) and they fit now as well with no rubbing. The slightly wider offset and larger tire makes the stance look much better IMO.

295/65/20's fit no problem.

Probably not. There is a need for both trucks. Each can have issues and do, I own both. When the tranny had to be replaced in our 2021 Gas HD, I was thinking dang, I wish I had the Allison. When the DEF heater went out last year on my diesel, the gas was sounding better but thats how it goes when problems arise, its human nature... There will always be back and forth discussions about gas vs diesel and there will always be exaggerations such as the comments you made. Bottom line, buy what you want and decide for yourself if it was the right decision. I personally prefer the diesel but have a need for the gas truck too and it works well and gets the job done.

I sold it a few years back but believe it showed GMC

My direction would be to wait for the part, not sure you have any other options. This happened to me last year, my truck needed an updated DEF tank that was on back order. It ended up taking 8 days but like you, they had me in a 1500 loaner. It sucks but happens.

Stock tires on +18 will fit no problem. I have +10 with 295/65/20 tires and just needed to tie back the fender liner a bit, everything else is stock.

I'm sure you checked this but any chance they got something on the HUD Lens in the dash? Adhesive or some type of interior detailer that could be blurring the display?