I am not totally sure about this, but all Ferrari's have a serial number. Since somewhere around 1980 a VIN (Vehicle Identification NUmber) was needed for the US market. That is why all cars from that era onwards have a full 17 digit VIN. The engine numbers used to be the same as the number of the car, hence we are talking about matching numbers in ads of auctions. If they don't have matching numbers, it means another engine is place in the car than it came with from the factory.
However, modern cars do not have matching numbers. I am not sure about how this is appointed, so can't help you there. I think it is just a batch number.
There is also a assembly number in each car. This should indicate which car was built first, and in which follow-up (not always the same series as the serial numbers)
As for the even/odd system, this ended with serial number 75000. After that, they used every number. You may notice that this is not the time when Fiat took over, but some 15 years later!
Niels