It looks like I'm going to have to get a used engine for my 1983 XJ6. Advertisers show a price difference between Federal & CA engines, although the VIN seventh digit is the same (3). Is there really a difference in the engines (excluding peripherals like cat converters)? I've seen somewhere on the web that the S-III engines are the same for both. My car was originally CA but no longer is registered there, and the cat converter has been removed.