TwistedPhil
+1y
Not positive on the GMC, but on the Silverados the core support, fenders, hood, bumper cover/ rebar/ brackets, grille, headlights, and marker lights are all different.
The radiator is also technically different, but the original can be fitted to the new core support.
I would imagine that the GMC is a similar situation- all pretty easy except for the core support and possibly modifying the new bumper brackets to fit your frame horns.
Good luck!