just a quick photo to show how i mounted mine
Rescued attachment speedo pickup mount.jpg

I'm just trying to work out exactly where that is?

on the passenger side looking from front at rear upright ,magnets mounted on outer lobro joint sensor on rear upright
tony

Ive only ever seen them fitted to the prop. What speedo you using?

cai telemetrix 140mph. only fitted it there cos i'm lazy only calculation now is number of inches per mile divided by distance covered in one revolution of wheel in inches times number of magnets as opposed to the above times diff ratio
tony
W~~~~~~~~d mount it on the inner joint

ive fitted mine there for exactly the same reason i.e. you take the diff ratio out of the equation but mine is on the inner joint