History of my Plymouth Valiant ownership

In California, these types of records are kept at the Department of Motor Vehicles (DMV) which is responsible for car registration. They are very uncooperative in sharing past records for research but quick to let you know if you owe them any money. I have done as you, unable to find a previous car. Try to go back to find the original owner yourself, where they lived, maybe info from the shipping company. I bought a cuda 30 years ago which contained an old registration card which contained their name and address. So I drove there to see- and yes, they still live there! That was just last year. Keep searching and post info here. Good luck.