My 51 Chev truck had its original engine replaced sometime in the 1950s. That owner had the title changed to match the new engine. In the mid-seventies I swapped that engine for another one from another pickup and sold that pickup. So now my title no longer matched the engine number. Fortunately again my title had the license plate number on it.
In time, in an effort to keep prisoners at the state prison busy, the state made everybody buy new license plates. I realized that if I got the new plate there would be nothing connecting my title with the actual truck. So I hustled down to the State Patrol for an inspection to talk them into using the number on the door pillar for the title. I explained the train of events.
The young officer began scraping the frame looking for a number with his flashlight, which he didn't find and was confused because GMC trucks did have frame numbers. He was about to impound the truck when a veteran officer came out to inform him that Chevrolet trucks did not have frame numbers. The old officer looked at the paperwork I had and at the license plate that matched the title and signed off on a new title using the door post number. Whew! That door-post plate was riveted on with special rivets and I've been very careful not to disturb them when doing body work and paint.