spaz,
I just swapped out the original donor gauges in 1108 for the new Autometer Cobra series. They are an Autometer copy of the Smith's gauges including the reverse 180 MPH speedo.
Autometer sales tells me that there are only four dealers for these gauges, Highland Daytona Racing, Kirkham Motorsports, FFR and Tristates Motorsports. I bought mine from HDR. FFR was still testing their's. Make sure you get the proper adapters for the mechanical hook ups, the proper "90 degree REVERSE" adapter for the speedo and the right fuel gauge for the Mustang sender, 16ohms empty and 158ohms full. I believe Tristates has the best price.
billk