I hope this isn't a shock to you. He passed on 12 years ago. Would you like me to look for an obituary?
There are 5 people in the area named Cooksey who have listed phone numbers on http://find.person.superpages.com/http://find.person.superpages.com/ (Use just the surname, enter "Modesto, Ca" as a place and check the box "Include surrounding area".)
If you have a cheap long-distance plan you could call them and ask.