Thanks for that info Truckin-on, that should help owners of newer cars to find the correct wire. I think the Blockleys have a lot of tread when new that alters the speedometer reading quite a lot. I set 004045 when they were new but they are about half worn now and I have 004100 to get the correct reading against my GPS, it could actually be closer to 004185 but I have gone with slightly over reading.
