I've done the exact thing on my 2018 HSE Lux without the rear locking diff. The part number I posted above the the one I used. You can swap it out without breaking your truck, but the additional ATPC button won't do anything until it's enabled with the GAP tool. The auto terrain response (TR2) also won't do anything until it is enabled. The control also has the dynamic drive mode selection, but the icon will be dark unless it is enabled as well. I never got the configurable dynamic mode properly enabled. I think my '18 is missing the electronic damping suspension and the front/rear accelerometers to make it work.

 

That's good to hear then. I can get the module with the TR2 and ATPC for about £150 on eBay. And I already have the GAP tool, so hopefully it shouldn't be too much of a job to do. I presume, as I already have TR2 from the factory, I would only need to enable the ATPC aspect? I imagine I would be in the same boat as you regarding the Dynamic mode. I have the build sheet somewhere from when my vehicle was new, so I guess I can check that for electronic dampers.

I notice that some of the modules that have the ATPC also have the trailer icon on the TR2 ****, I wonder what would be involved with enabling that feature?
hopefully this link works, but if you notice this one has the ATPC button and the Trailer icon, but doesn't appear to have the Dynamic mode.
LAND ROVER DISCOVERY 5 L462 CENTRE CONSOLE SUSPENSION MODES SWITCH 2016 | eBay UK

 

If you have the 360 surround cameras then you *might* be able to enable the trailer steering assist. The **** with the trailer icon pulls up and lets you steer the truck while reversing to maintain the trailer trajectory. Cool stuff. But as I understand it, it only works with the 360 camera system.

 

I do have the 360 system. Although the right hand mirror camera is showing the image at the wrong angle, haven't worked out how to fix that yet.
If I was able to enable that feature as well that would be quite cool. I can see it as an option on some of these retrofit sites, but it's a $700 option where the ATPC is only $50. Which makes me think it's more involved, but that could be because it requires the 360 cameras. Unfortunately the site doesn't detail what you are getting for your $700!