The deadline to upgrade your Ford L8000 engine to a 2010 or newer model engine was January 1st 2015. You can avoid having to replace your engine by reporting either as a low-use diesel truck or low-mileage diesel work truck.
Low-use will not require a PM filter, but will not allow you to drive the truck over 1000 miles a year. low-mileage work use will require a PM filter and allow you to drive your vehicle up to 20,000 a year.
No smog inspection (similar to that of passenger vehicles) is required. The CHP and ARB do conduct smoke tests however, which you should familiarize yourself with before selling this truck.
Please visit http://www.arb.ca.gov/msprog/truckstop/truckstop.htm for very helpful information pertaining to commercial diesel trucks operating in California.