Gearbox help, please

[Ste46]

My 206cc, 53 plate 04 year, 1587cc petrol, is in need of a gearbox replacement. There are several available for sale, but under a variety of part numbers. Some even seem to be common to the Ford Fiesta!
How can I ascertain which one I need for my car (5 speed manual)? are they all the same fitting/clutch size, albeit with possibly differing internal spec? and any ideas where I can find the part number on my gearbox?
Any advice/information would be greatly appreciated.
Many thanks in anticipation
Steve

[IanL]

If you post the last eight digits of your VIN, I can look up the Peugeot Part No and markings for your car.