i am fitting an ellectric speedo can any one tell me how to get it working for the mph to work correctly. do you need some sort of sencer,and where to put it,or any ideas will do thanks

[Edited on 22/3/07 by arse2000]

It depends upon the speedo used.
Some use reed relay sensors which pick up a signal from magnets mounted on a rotating surface (e.g. propshaft), other speedos use a variable reluctant sensor which picks a signal from being near a spinning bit of metal (some people use diff bolts, some people (like me) make up a trigger wheel specifically.... The advantage of the magnet based system is the gap between the sensor and the magnet can be bigger than with a VR sensor which typically can only handle a 0.5-1.5mm gap.

many thanks

Some gearboxes have built-in sensors (MT75 for example) so it is worth checking.