My dad put seatbelts in a 53 Ford wagon (probably 1955) and iirc they were an option that he paid for in a new 57 Ford wagon, first new car that my dad bought.

 

Your dad was ahead of his time. 1956 is the first year seat belts were available as an option.

 

I snapped this picture at the Spring Rod Run at the Daytona Speedway and though it was kind of neat.

 

Most of the early devices were mis interpreted - They weren't Child Safety - They were for Child recovery
My Mother used the old school straight arm snap, it was faster than a rattlesnake - At sometime between my youth and my mid thirties She must have spent some time in a right hand drive country - I was helping Her move, She was riding in the passenger seat - I said something to Her after the second time She hit me - She just looked at me and did the What Thing

 

My parents were friends with a couple where the wife fell out a car when the door popped open on the passengers side going around a corner and she died as a result. That accident occurred shortly before Dad had seat belts installed in the 53 wagon. My first car was a 57 beetle which I installed shoulder belts in. That would have been 1963. Willard, my F-1 has shoulder belts.

 

A strap like that would have prevented my hard head from breaking the windshield in my parents new '72 LTD as my Mom got used to the new fangled power disc brakes. 😊 I think they had the car less than a week before the windshield had to be replaced.