unlocking a chevy express radio

[msc520]

i purchased a factory radio for my 2006 chevy express rv the radio came out of a 2005 gmc van would any one of you fellows know how to unlock this radio the auto salvage yard i bought it from says its locked when they went to test it after they removed it

[PaulD]

it will become "locked" when you disconnect the radio from the battery.

[murd3rd]

dealer will provide ya the code for 20-30 bucks