Get the parts and put them on! No change should be needed! That is one great thing about the GMC's any body parts from one year will fit on any other year with only two small exceptions: One is the obviouse no marker lights in 67 and the other is the doors in 72, you can use a 72 door on any other year but a 72 inside door panel will not mount on any door other than a 72 year due to some additional bracing that was put inside the door!
