What is a "X" engine in a '96 VIN Code?

Hey to all. I just picked up a 1996 Mustang GT and in working out the vin code, I find the letter "X" in the engine location. I see codes for a "4", a "W" and a "V". But no "X"....Please set me straight! Is in not just a 4.6 ? Thank you.

<font size=-1>[ This Message was edited by: planetdirt on 5/13/06 12:20pm ]</font>

<font size=-1>[ This Message was edited by: planetdirt on 5/13/06 12:22pm ]</font>