Tool Box Open with no Key/Latch ?

[Ironhorse]

I have a '70 3/4 ton 2wd CustomCamper/20 with the bedside tool box option. The door does have some rust as usual but I think it can be saved. Have all three pieces of the tool box trim and the fiberglass box is unbroken. Problem is the keyed latch is gone and I don't seem to be able to get the door open to remove the door and related parts. I've tried using a putty knife to "push" the inner latch slide down to release the door with no luck. Any ideas that will not destroy the door or box? Think if I can get it open and removed someone could use it for their tool box bedside.