Charlie (Charley),
Brad has nicely explained this situation. If you post the various codes that you have, people will be able to help you figure out a variety of things related to title, registration, engine serial number vehicle serial number (vehicle ID), etc.
- the engine serial number is pressed into the block just to the rear of where the distributor goes into the block
- the vehicle (cab) serial number is on a metal plate that is screwed or riveted to the cab between the driver's side door hinges
Either of the above codes might have been used on the title and/or registration.