I am looking for a double cylinder deadbolt lock for an unusual application, an aluminum plug door on a bus. It currently has a simple tubular latch assembly with a plastic tube through a flange held into the edge of the door by two screws. It has a round sliding pin latchbolt of about 10mm in diameter. The bolt is actuated by a cam lock mounted to the outside face of the door, with a large aluminum cam that pushes a boss on the bolt when turned in one direction, and pulls it when pushed in the other.
The lock holes are arranged co-axially like a typical bored lock with a backset of 70mm, or 2 and 3/4 inches. The outer hole is a 17mm slot in a 21mm hole, and the inner hole is 37mm.
The really difficult part to match is the width of the lock front, which can only be a maximum of about 16mm, or about 5/8 inch because it has to fit in a groove in the outside of the door which holds the rubber seal. If a mortise lock is used, the case can only be this wide. The lock armor/front could be a little bit larger if it were removable, maybe up to 19mm. However, there is very little space for a lock case, only about 74mm assuming that the cylinder location is correct. I have been looking for mortise locks for security reasons, but the only ones I can find which are around the correct size are vintage.
The other complication is the space available for the outside cylinder housing. There is plenty of room for a typical mortise lock cylinder, but there is not enough space for the housing on the average bored hole deadbolt lock. They all seem to be about 2.25" in diameter or larger, and there is no more than 2.2" of room. A little massaging is acceptable if the housing can afford it.
The door is 37mm thick, or 1.45 inches. The width of the interior space is about 31mm.
Can anyone suggest a lock that will work, or can be modified to work? It has to survive full weather exposure on top of everything else, and hey, I'm also trying not to go broke in the bargain.