http://www.courtinfo.ca.gov/selfhelp/smallclaims/#/resource.htm
This Web site has a ton of information on small claims.
You can go to the DMV to see where his truck is registered using his license plate.
Then what you do is just mail the forms to his old address. After 30 days, when he does not respond, you sue him and then when you win in court, you put a lien on him through County court that appears on his record and doesn't go away until he pays up. You may never get your money back, but you will mess his life up. Good luck.