Today i purchased a new speedo sensor from ford, at a cost of nearly £30

I can't locate where it is on the gearbox? Its not underneath, and i cant see anything from the top? The new part is a long black plastic thing, with a plug on the top ?

I also found the cause of the exhaust rattle, the top heatshield on the CAT has come off, and is wedged between the cat and the gearbox, so i need to force it out somehow tommorow.