The doors and latches are different on a 40 and 41. They both will fit either models. The difference is the 40 latch comes off the back and is mounted on a plate. The door panel has no access hole to repair the rear door.
The 41 door latch is mounted inside the door and has no latch panel that comes off. The door has an access panel in the middle to repair any damage and remove the latch. Original ones are difficult to find so keep trying. If building a hot rod, use a bear claw. Hope this helps. I have pictures of the above if required. PM for pictures.
