What type of engine does the '96 Cobra have?

A friend of mine is interested in buying a ’96 cobra. The owner of the cobra says that in ‘96 Ford offered a few special run cobras with a all aluminum engine, and of course this particular car is one of the all aluminum cars. Does anyone else know about this? I haven’t heard about the 2 different engines before.

I assumed they were all the same(alum), esp. when '96 was the first year of the 4.6. I don't know what the hell this guiy is talking about.