Its been wired to my cab by work - I think it is a fuel monitor but want to make sure it is not a tracker.
On the box is marked FORD with a lot of numbers including E13 10190 and the letters SNP

Thanks
Will

Quite frankly what is the difference? If this is a work vehicle then they have every right to know your whereabouts during the time you are in the vehicle. More than likely it has something to do with your fuel consumption but not knowing what type of vehicle it is installed in or what kind of company you are employed by it's hard to really tell. Why not just come out and ask them what the box is or ask one of the company mechanics what the box is. If you are say a delivery truck person using that truck it could be a kill ignitition switch in case the vehicle was stolen.