From memory; 4/4s came with Zetec 1.8s (belt) upto about 2005 and then went to the 1.8 Duratec (chain).
My 4/4 is a Zetec and though Ford say belt change every 100,000 miles; I had mine done at 7 years old for peace of mind.
Bud

Bud
4/4 "Stanley"