If no one can help finding K-Line doors I would first see if I can find doors from other cars that would fit, then try and find beaters at train shows and auction sites. If the doors are unique to that car and you have another car in your collection that has the same door, use one of them to cast resin copies. Not hard to do and you will find other uses for the molding and casting compounds. I have made a number of freight and passenger car doors and other parts this way.
Pete