Cut and install door stiffener tubing HD-17 and secure into place with gussets HG-4, riveted into place with HM-14 1/8" rivets.
Install door latch guides HD-18 on door stiffener with 2 1/8" rivets each and drill hole in stiffener with 7/32" drill. Drill 7/32" holes on door posts and adjust door latch to correct length and rivet into place with 1/8" rivets (3 in each).
