welcome to the garage, sweetpea .... originally there would have been a key lock on the pass side [NOT in the handle], with the driver side locked from inside - sometime in the last 65 years, yours got lost
many of the vendors will have the parts you need,
like here, and
here .... the only 'foolproof' way to prevent theft is to keep the truck in a locked garage at all times, although a battery disconnect switch can help
Bill
