Did you try dig up the dealership details? Did you contact the DMV from the town it was sold in for information? Here's a post I made a long while ago about hunting previous owners, this is in regards to another post on a different site so some things may not be applicable. The jist of it is the same, '75 T/A = '78 Marty T/A. Did you press the previous owner for information where he got it from? Did you run VIN checks on the car and see if anything comes up from the '90's? You will find him if you really try to look for him.
Next suggestion, now I don't know what the legislation is in Cali, but in Texas, I called a DMV and asked about any information they may have had about my car. They made me fill out something I think was called a Freedom of Information form. I filled in the form and gave them the licence plate number for the car (which hadn't been in use since 1997) and the VIN. Two weeks later, a type-writer written document with... get this...
The previous two owners AND their contact information as well as addresses. I'm not kidding. You pay a fee and they give it to you. Depends on the criteria of the form, there were a few reasons to tick on the paper, but I don't know what the form is like in Cali. I believe that only works up to a certain point though, that may have only been for cars older than 20 years old etc... I called the DMV twice, the first woman who answered the phone was EXTREMELY arrogant and unhelpful. The second person was this old guy who used to have a T/A, so yada yada yada a few minutes of talking later, he was were happy to help. Good to have friends in high places, really depends if the person gets paid enough to care.
The next thing is that the car was sold recently. (Last ten years) Now that's good, because if any registration was transferred, it's on a computer database, not a 30 year old type written document. So the information is there.
