As far as I could tell you needed specific arms from Wicked Fab to run the aluminum knuckle.
Could just be required for GMT-800 but I think 900 will be the same way.

 

they did say that you would need bigger ball joints because the aluminum is physically larger.

 

When I get into things like this I go and look up part numbers for each vehicle and see if they crossover. I went to Belltech and Moogs websites and found the same part numbers under each year model (generation) truck you mentioned. I checked part numbers on the upper control arms, lowers, and spindles. And all 3 components had the same part numbers available for both trucks. Which tells me they fit.

The other thing I do is see if any companies list parts that show to fit both, in the description. So I went to DJM and their upper and lower control arm kit, shows to fit 2008-2015. Im not sure why they didn't put 2007-2018, but I do see this alot where they for some reason don't include all years. However, if you have a 2008 or a 2015 the kit is the same from DJM. Which is another indicator the parts are interchangeable between the trucks.
https://djmsuspension.com/product/20...-control-arms/

I've been under the impression the frame is the same on the GMT900 and K2, as a technician everything I touched looked the same but google says they aren't the same... so I don't know.

So, it looks like you can put 14+ components on your GMT900. You just need to make sure you match up which parts work with each other. And the simplest way to say it is, it's all the aluminum stuff goes together and the steel stuff goes together.