Correct, Glenn they are totally different engines.

Your mate currently has a 'Sigma' engine or Zetec SE, this has nothing in common with a Zetec-E, the exhaust and inlet manifold oppose each other, plus it's heavier, thus suspension is different etc.

There has been a whole list before, but suffice to say there are several differences between the engines.

The 1.7 Puma engine is just a larger capacity engine than he already has, therefore it will fit as far as I am aware without any mods.

Martin