At first I was going to do nothing more than to add in dual zone climate controls to my truck, but along the way while doing research on this I've learned a LOT of stuff, so I've decided instead to go further with this swap than just dual zone.
If you want the quick answer to a dual zone swap in your truck, here it is:
It can be done, you need ONLY the climate control head, and HVAC housing and the wiring on the HVAC housing. The one single wire for a dual zone setup already exists in every dash wiring harness.

That being said I'm making this thread to keep track of this entire conversion I've found out can be done.
I will come back and edit this to include a ton more information that I picked up, but long story short for right now, you can convert an SLT to a laramie with the right dash wiring harness....but it IS work and expense....a LOT of it, for just comfort options.

But guess what? I've never been, and probably never will be able to be the guy to walk into the dealership and order a new truck with every check box ticked off.....so instead I've discovered that I can add a **** ton of features to my old truck instead

The wiring harness 56051212AB is the dash wiring harness with ALL of the options (Adjustable pedals, steering wheel radio controls, heated seats, electronic shift 4WD) so by swapping out this harness you will have all the wiring needed to add in any of these features, or just leave them unplugged if you don't want them....but if you don't want them then why are you reading this?

So I'll just leave this here for now and see if anyone has anything to say, and update it as I go.
I've seen so many threads talking about the dual zone swap but nobody has ever seemed to go through it for whatever reason.....well, this has driven me to be the one to actually do it.

Total cost so far?
HVAC Housing, Pulled myself from local wreckers - $175 CAD
Entire Dashboard with wiring harness, infinity amp and speakers pulled myself from a wreckers 2 hours away - $339 CAD+ ~$100 gas.....but my truck is terrible on gas right now....yes I paid too much for this I know I did, but it was the ONLY available dash with the wiring harness I needed in Ontario, so I jumped on it.
Unfortunately some redneck ******* has rednecked a head unit into it and cut a bunch of speaker wires, so I'll have to enact fixes to those wires....easy enough, though I am displeased by this.

Be aware that a harness for a 2005 will ONLY fit a 2005 as connector C206 in the passenger side A pillar is different between 2002-2004. up to 2004 it's just a 2 pin connector for roof lights. In 2005 it's a 6 pin connector for roof lights and the mirror. This is the same between 1500, 2500 and 3500 for their respective years.

 

I was incorrect about dash wiring harness part numbers.
56051215AB is the harness that includes all features from what I can see.

This harness has sales codes: CMA and RCK. This makes no mention of sales code XAP which is adjustable pedals, however I have this actual harness in my hands physically and I can absolutely confirm the following options being available on this harness with this part number. It may be that XAP isn't mentioned for this particular harness as the build sheet says the customer didn't want the adjustable pedals, and so got a credit for "adjustable pedal delete"
I can provide build sheets for the VIN I pulled the dashboard from.
56051215AB Available Options:

Adjustable pedals (XAP)
Heated Seats (CMA)
Power Locks (JPB)
Sentry RKE (GXX)
Infinity Speakers (RCK)
Speed Control (NHM)
Steering Wheel Mounted Audio Controls (RDZ)

These are the features I can 100% confirm so far having the harness right here in my hands, and having seen the options that were on the truck that I pulled it from.

 

I have been reading yours posts and threads. thanks for the info you are providing. You should be commended for your energy and enthusiasm. ☺ good job and good luck with everything! Keep us posted 😊

 

I hope it's useful to someone out there. Maybe it's a moot point now but there are a lot of threads talking about a dual zone swap but none of them ever provide any real information and it looks like once a person has said "it might not work, you'll need all this wiring" then whoever was asking just gave up and looked no further.

Most of the posts are like super old though.

I just decided that I was going to do this because it apparently hasn't been done and everyone thinks you can't do it.
I however think that you CAN do it, and so I'll try lol.

I've got the full service manual, part numbers book and sales code list. I've been digging deep into this for the last couple of weeks, and have been looking into it as a whole for probably 2 or 3 years now.

 

Here's the dashboard I pulled...... no real to post it because we all know what they look like lmao.

I pulled the whole dash because it's going to be a hell of a lot easier to just remove my dashboard and drop this one in, as opposed to pulling the wiring from this, removing my dash, pulling my wiring from that, installing the new wiring and putting mine back.
This also includes the infinity amp and dashboard speakers, so a little bonus there.
HOWEVER.....
some ****ing idiot decided that the best way to install the stereo was to hack up a bunch of the amp and speaker wiring and just run his own wires.
People need to stop doing this crap and just do things right. get the right adapters etc....don't go hacking up wiring.
To make matters worse they didn't even solder that ****, just twisted the wires together and added some heat shrink and/or electrical tape.

I'll fix it up good and proper though, with solder connections and adhesive heat shrink.

Anyway, I still need to get the black cap for the dashboard instead of this ugly tan one, the adjustable pedal assembly, the switches for the heated seats and a steering wheel with radio controls.

 

I think I have only seen one adjustable pedal truck in the jyards... it was a 2002. I thought about taking it, but didn't - its since been crushed.

 

I had to make a 5 hour round trip to get this dashboard since there were no others in any yards near me.

I know there are the pedal assembly and a couple of other things at yards near me so hopefully they'll be there for a while until I have money together to get them.....but this can be added after the dashboard has been installed, so not a huge concern right now.
the priority was getting the dashboard since it was so hard to find. I'm sure if I had any patience I could have found one without the radio wiring all hacked up, but I can live with that I guess lol.

 

ok, so it turns out for the FULL option package wiring harness 56051216AB is what's needed. This one also includes the bluetooth module wiring.

as it stands right now I can't find one of these harnesses ANYWHERE and I can't figure out what part I would search for at car-part.com to find the right truck.

What I'll do most likely is use my current harness and just keep searching until I find the 56051216AB, and then I'll most likely go all out and do this again lmao.
but we'll see, I can't really predict how the future will go, so I'm sticking with my current plan for now unless one of these magical harnesses becomes available.

 

Search for the bluetooth module. Should be able to get the correct harness from the truck that has the part.

 

car-part doesn't have bluetooth anything as an option to search for. I went through the entire list yesterday and couldn't see any part that would result in finding the right truck.

At any rate, I'll go forward with this and if the harness becomes available at some point then I guess I'm back to ripping out my dash again lmao.