Hi there hope i can of some assistance to you.
Could you explain your situation a little more?
Are you the original owner of the vehicle?
Can you let me know what stereo your vehicle has in it i.e 6000cd 6006cd etc it should say on the front of it.
Ok then the old style radios like yours unfortunately there is know way of getting the part number and serial number out of the set without taking it out unlike the new ones where you can get the numbers by pressing certain buttons.
Now there are two ways of sorting this out, first way is to go to somewhere like halfords and by the radio keys for around £5 then take the radio out and give me the numbers then i can get you the code.
Second way is to look in your book pack and see if you can find any information telling you the original suppling dealer of the vehicle from new, if you can find something then phone them up and ask them for the code and as long as it is the original stereo then it should work, now sometimes they will just tell you and sometimes they will not for security reasons in case it has been stolen.
Not sure about that think it only comes up once i have answered the question not when i ask for information. get the information of the set and i will sort you a code out.