[Ant]

Thanks guys, I was complicating the issue, as in the past I got an old Smiths speedo from the wreckers, these varied in a lot of old cars, all different turns per mile etc, imported a 180mph gauge face from the UK and then after calculating the transmission/tires and rear end, if it wasn't right I took it in to a speedo repairer and they altered the magnetism of the instrument, but with these you are unable to take the gauge apart unless you reweld the plastic case.