Alot of places sell the Z code tranny; D&D, Hanlon, FordSpeed and Steeda to name a few. They're currently running in the $1000 to $1100 range the last time I checked. You can also order it directly from your Ford dealer as part number M-7003-Z. You can upgrade (if that's what you want to call it) your regular T5 to Z code specs, but it requires the cluster PLUS all the I/O gears...not an inexpensive undertaking. If I had to take a guess, I'd bet that the changeover would cost upwards of $800 just in hard parts alone. That's only a few hundred less than a brand new one.
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Jeff Chambers
T/S #3
11.86 Seconds/113.8 MPH
Chambers Racing Team