Hi,
I have a 63 c10. I know what you mean. It's actually a pretty good theft deterrent.
However, i understand your worry. I have no lock holes on the outside of the passenger door either (only locks from the inside.) The driver door you can shut and lock with a key on the outside.
You can do a couple things:
1. You can always carry your keys and lock the drivers door from the outside and lock the inside of the passenger door (first)
2. You can remove the inner door mechanism where the lock handle is and weld a piece over the hole and leave the latch part on the passenger door for the outside part. This way you can still open/close that door from the outside only.
3. Same thing, but instead of removing it, cut off the part and make sure it's on the "open" position before you cut off the inside handle part.
4.a You can just remove the rod and keep the look of original and this way the outside latch only works and you'll have to open the window to let yourself out from the inside.
4.b Ask "MagGyver" for some insight....
Good luck.
