Your only real option at this point is to replace your Ford F-250 truck's catalytic converter. We can recommend contacting the State's smog check referee's office for a hardship extension but being it that a vehicle is ineligible for the State's CAP program (consumer assistance program) if it has any missing or tampered emission components we're not sure if the referee will allow you a hardship waiver. A Hardship Waiver basically exempts your Ford F-250 from a smog check for 2 years, but requires you make appropriate repairs before your next smog check required time period.
You may contact the State referee at (800) 622-7733 to see if there is anything they can do for you. It might not hurt to have your police report describing the stolen CAT as well incase the Referee offers some sort of assistance. We hope they can help you.