The original VX sales brochures are quite useful in giving the options available for each particular model when new. This includes the particular radio systems available per middle. There were usually two publications issued each year (the date is in the outer rear cover), so you need the correct era for your car, not forgetting they are printed in advance of your car rolling off the production line.
Alternatively if you go to you local (friendly) VX dealer he can print off a list of the actual equipment fitted to your vehicle when new.
I say friendly, because it involves pressing a few more buttons on their keypad, and often the CBA or 'too hard to do' attitude kicks in. They can do it, because I have asked and got the necessary details for my cars.
There is also a German website which can supply this info - all you need is the chassis no.
I don't know whether the website is still going, as it was a few years ago when last did it, but I can check this evening if it is still current if you wish.