Djcarter140

I have a 2015 Chevy 2500 it had the 4 in screen with back up camera and my link I want to go to a 8 inch screen. I bought a radio off line what else do I need? The hmi module? Do I need a 2.5? I don’t care about navigation I just want to be able to use my phone through radio and have a bigger back up camera. I’m so confused please help