Researching original owner?

There are websites that with that info you can do people searches.

Spokeo is one of them.
Small fee for a bunch of info like children etc.
Spokeo - People Search | White Pages | Reverse Phone Lookup

Find the local news paper in montana and talk to them about running a story about the car and your search for the owner on the certicard


Or hire a PI

Just googled Marvine. He has a surviving son and grandkids.

The obit on his wife has all the info you need.

Vivian R. Randall Obituary (1922 - 2018) Great Falls Tribune

Google the names of the son and grandkids in GT. Falls Montana and start sending letters.

My bet is you will find one who can shed some light.

Just be very respectfull and realize that this car might have good memories or bad associated with it