I simply bought a used 67/68 150 MPH speedo for $45 and had it refurbished for $59 and swapped them out. It wasn't that hard. I also got the trip odometer and twist knob with the 150 speedo. The hole location for the twist knob is in the dash already so it made it easy to convert on my '69 Barracuda.
So to answer your question....no, I haven't
treblig
