Hi,
Can you give us wee bit more to go on, the year of the vehicle and type of engine i.e: 2.5 diesel, 2.5 petrol, 2.25 diesel, 2.25 pertol, 200 TDi, 300 TDi, V8 or TD5 would be handy. :p
With this info then I'm sure someone will be able to give you some info on what starter motor you have and maybe even a part number.
Also, tell us a bit about the problem you've got with it, someone may know how to sort it or know a short cut. :D