the zetec SE 1.6 are mostly the same and have nothing in common with the older Zetec E/R engines with silvertop/blacktop designation.

The zetec SE was available on the focus from first release to the current day with several revisions on the way.

In terms of the Zetec E/R engine, 1998 was the cross over year for silvertop/blacktop so in theory it is possible for some of the earliest 1.8/2.0 focus to have a silvertop. Wether ford let this happen or not, I do not know, but on date alone it is theoretically possible.