We repaired the cracked lift gate yesterday. Welded in a new small plate around the top to accept the hinges.
Painted and lubed the hinges. reinstalled the window glass with a new seal from Steele Rubber.
Then installed the liftgate-to-body gasket (same gasket is used on the front two doors). And then, Reassembled all parts - it works very well!
Lifts and closes easily, and mates well to the body. A successful repair!