Abstract: For a prehung door unit of door and door frame, a locking assembly lock together the prehung door units irreversably until after permanent final installation, a portion of the assembly is removable from the door's latch bore through the doors lockset bore. The assembly achieves its benefits by thus allowing factory "bench" final settings of accurate door mounting parameters of plumbing and leveling fixed relationships relative to its mounting frame. The fixed factor bench plumbing and leveling settings are maintained by the installed assembly before, during and subsequent to artisan mounting the fixed immobilized movement of the frame within a door jamb, precluding heretofore necessity of artisan time-consuming and costly plumbing and leveling a frame mounted door during installation of the frame and its door of heretofore prehung door units.