Radio code - long shot

[Tihol Tiholov]

Greetings,
Got this '99 VW Mk4 radio (single DIN) from a Golf/Jetta with a Eurovan I
bought. Was bought privately, so no transaction papers. PO forgot to ask
for the code, so it no worky. I've replaced it with an OEM Heidelberg since
but hate to have it just sit unused and looking pretty. Is there any way to
find out the code? If dealer only, how do I convince them that it's not
stolen?
There are a bunch of various numbers and codes printed all over it but none
(of course) seem like the 1 to enter.

Thanks,
-- 
Tihol