2014 gmc sierra radio install

I have a 2014 gmc sierria crew with onstar/ without bose. I am trying to install my new double din with nav. I have all i need the pac kit the metra dask kit. just waiting on my headrest monitors to come in. today i took it apart and looked behind the screen. i see the cd player that needs to come out but now sure what else needs to come out. it looks like maybe the onstar intelilink maybe but it has the plugs for the pac terminal that needs to plug into. i see the back up camera plug. does all this need to come out. looks like some fabricating is going to be done to open the opening. I do not have any reputable installers here i ave done my own work since 1995. but have not seen this before. I have 2 sundown 12 onder the seat with sundown amp. just need this double din nave unit installed. any help would be great. thanks

There are instructions with the Metra Dash Kit. They will tell you what you have to cut and what you have to move.

the kit that i got only shows me how to assemble the kit to my radio and to install it in the truck not what i need to replace or remove or cut. thanks

Awsome. Thanks

Ok I have the pac rp5-gm51. I have rear speakers and subs only. No front speakers and no signal to the back up camera. All out puts on radio are good but no front outputs coming out of pac and no backup signal. Pax audio no help they are stunned. Help please. 2014 GMC Sierra with on star without Bose. Facrory back up camera.