Hi Christina and welcome to A2K.
As I'm sure you've guessed, this is not a great way to look for your Dad. It's very hit or miss, and you never know who's telling you the truth. One thing I would suggest, if you want to spend a little $$, is hiring a skip tracer (just look them up; they're in the phone book). These are people who look through older records to find missing persons. I would also strongly suggest talking to your mother and to your grandparents if they are still alive and see what they remember.
Best of luck to you.