You can absolutely take a GMC sierra, or a GMC Dinali multi flex tailgate off of one of those vehicles and put it on a Silverado 2500. You were going to need to go to the dealer and pick up the wiring harness if it did not come with the multi flex tailgate, and it will plug into the body control module near the spare tire. The interesting thing about the wiring harness is that the body control module puts power to both switches, but the upper switch for the small tailgate will not operate. It took a few hours running through wiring on the harness to realize that I could open both gates with the same switch so I wired the smaller gate to the large gate so that they both open at the same time. This does not bother me, and I do not have a hitch in the receiver where the small gate will come down and smack it.
