Fitting the Zetec into the ZX2 put the filter directly in the way of the steering tie rod. A skinnier but slightly longer filter was the solution. That same filter is specified even when the Zetec is in a different vehicle for all Zetecs after the ZX2 was introduced.
Be a little careful about what filter you use on a Zetec though. I remember being involved with a siezed engine in a ZX2 that had an oil filter installed by a quick lube shop that was intended for the non Zetec engine. The insurance company for the quick lube shop paid for a new engine.
Even with that said, I regularly use a filter specified for the Festiva (a Motorcraft FL 810) instead of the smaller Motrocraft FL 816 on my 91 Escort GT. I like the larger filter with more filter media. Such swaps need to be done with care though so you don't end up with problems like the ZX2 mentioned above.
