If it's a UK car it will have been imported through Maranello Concessionaires - you can contact them on 01784 436222.
Not sure if they'll have this information - but if they don't you'll struggle to find anyone else outside of the factory that would be able to tell you. They keep meticulous records of all the cars they sell.
uhm, if you own the car, you can register yourself at the owners site owners.ferrari.com. I believe you can get some info there on your car, but I heard a lot of people who weren't very fond of the site. I think the best is to call the importer, they have direct acces to the factory.
Getting information from the factory is very difficult. I know a writer that has recently written a historical article for Ferrari. He is now trying to get history information instead of money and it is proving difficult. Then again he is trying for a car in the 1950s
Your Mondial should have a manufacture plate on the driver's side door jamb which shows a build date; month and year anyway. Now that you've found the Ferrari Owners website, you can request a heritage certificate which goes into further detail.
You'll have to register at the site. Just complete their questionaire completely certifying your ownership of the Mondial. Once registered, you can click on "Heritage Certificate" on their menu to apply for the certificate. You'll need information regarding your chassis #, engine #, gearbox #, etc.