Speedo Sensor
 

What and where is this and what is a good second hand price?

It may be on the top of the gearbox just above where the r/h drive shaft comes out the box, or it may get its speed signal from the abs system.

The Yellow blanking plug right in the centre of the pic is where it'll be if the speedo is driven off the gearbox

http://i4.photobucket.com/albums/y14...ps5a17febd.jpg

Oh not that bloody thing again!

i could be wrong but i was told it was linked off the offside rear. and seeing as though when you accelerate on ice for example the speedo doesnt read crazy speeds as it does on cars measured off the gearbox or front wheels