Why do I see a B74F instead of the B747 passenger version?

FSD ("the VATSIM protocol") uses the aircraft and airline ICAO codes to identify other pilot's aircraft. Unfortunately many use pseudo/fantasy ICAO codes. Our source for ICAO codes is the official ICAO database.

As an example let's look at the B747, as you can see neither B747 nor B74F are valid codes. That means, by using official ICAO codes there is no way to distinguish a freight B747 from a combi or pax version.

It is though possible to use different liveries to distinguish those planes, e.g. by using the passenger and cargo livery for a very plane (if there is any).

Unfortunately there is no standard at VATSIM of how liveries and ICAO codes are are really to be used. Every client uses its own logic. For instance swift <-> swift communication transfers more details, and XSB has its own livery schema. But there is no standard.

If you want to achieve customized results in swift you have the following options: