radio codes

[roby02]

got a problem
i replaced my original head unit in the Vt for a custom setup some time ago and somehow threw out the original headunit ( i think it got damaged)
now im getting car ready for sale i bought another headhunit via ebay it came with the code but cant find the ruddy thing
i cant contact seller as they are no longer registered on ebay
so does anyone know if or how i can get the code for the unit
thanks

[Ratten]

I know with the diagnostic tool we have it shows the pin for the stereo, but im not sure if that is for the one that it came out of the factory with or for the one its been changed over with if that makes sense?, im just a locksmith so auto elec's diagnostics tools could be more informative on that side of the car cuz we only use it for programming keys in and such