Electronic speedo conversion

Hi All,
 
Has anyone done an electronic speedo conversion in a street escort.  Both my tacho and speedo are giving me the [link=mailto:s@#$%]s@#$%[/link].  I can get a programmable speedo from the US which I think will fit in the binnacle of my RS but what to use as a sensor is the big question. They offer a sensor which will possibly fit in the original speedo hole in the box but will have to take out the drive gear, which I presume will involve pulling the arse end of the box off to get to it. I have a type 9. A tailshaft mounted one? I have seen some pictures but don't know how they work.  Suggestions anyone - race/rally car users in particular might have retro fitted one of these.
Cheers,
Len

Not sure it helps, Terratrips and the like usually take their input from a sensor mounted on the front hub, similar to an abs sensor or vr crank sensor. Maybe you could adapt similar to an electonic speedo rather than use a gearbox sensor.

I had a setup done from using a Falcon xe/f electric speedo drive in the Manual gearbox And used the same Falcon dash speedo .. It's seemed to work Ok but sold the car on before it was perfected. The car was a mk2 1600 more door.

The Falcon speedo face was carefully removed and the escort one fitted on with slight mods to mount it to the cluster.