On the AD trucks, there's a code on the door lock cylinder. If you can pull the door lock out, you should be able to get the code off it.
The codes were the same from 1935 thru 1966. More info in
this post. Scroll up 2 posts from there and DADS50 posted a pic of where the code is on the door lock.
Most any locksmith (not the key duplicators at the hardware stores) can cut you a key if you have the code.
If all else fails, send me your ignition lock and I can see if I have a key that will fit and send it back to you. I've collected about 150 different keys.
