serpintine belt or timing belt

It has to be 3.0 for a 6 cylinder not 2.0 it has a timing chain

Both engines run chains and the 4 cyl should be a 2.3 litre.

Well to be a bit of a pain, it depends on which country the car was built for. They used a gas 2.0 LF-VE version of the MZR (aka Ford Duratec) and a diesel 2.0 based on the same engine in other countries.

Both of those use timing chains for the camshafts but they also use a serpentine belt to drive the external engine accessories like the alternator, power steering pump, A/C compressor and such.