MonkeyBoy

On a C4 cab, what are the differences between the model years? I know that the 97 and 98 have the child seat airbag deactivation wiring, but what other differences are there?

Patentman

On a 1998 993 how does one deactivate the passenger side airbag? Is there some switch somewhere?

solsrch

I don't have a '98, and don't know for sure, but I think you have to use the proper Porsche child seat, like with a Boxster, to deactivate the air bag. As an alternative, you can modify any year to install a keyed switch allowing deactivation when you have a child in the passenger seat. The parts cost around $150 as I recall and install is about the same amount.
My kids love to ride in my Porsche and going from an older model to one that had air bags I wanted to make sure they could ride with me safely.