I bought it used off someone on here, and didn't write the part number down...dooh
the polo base looks identical to standard golf base, bit boring, somehow they have squeezed in DAB circuits as well!! , you can fit any screw in antenna you want, yes the polo is more stubby and a different sized thread.
the vw dealer should be able to sort you out with part numbers, there are loads of different ones, bit of a nightmare...........