This post reminds me that the drivers door on my 54 Chev 2 ton don't have a key lock whereas the passenger does. The ignition key does work to lock the passenger side, IS THIS A NORMAL SET UP OR HAS SOMEONE CHANGED IT? If it's a factory setup why would they do it that way.
All brands of trucks used to be like that. I believe the intent was so you would exit the vehicle on the curb side instead of into traffic. This has been discussed here numerous times over the years. A search should turn up lots of interesting reading.