The Altman kit is an option if you have a spare $340 laying around.
http://www.lmctruck.com/icatalog/CBE/full.aspx?page=15
If not you would need to cut about four inches above and below the striker and the portion of the door holding the latch assembly from the donor truck. Then you would have to align everything on your truck, cut, weld, realign and figure out the locking mechanism and latch release linkages.