Winchester 101 Shotgun Serial Number & Barrel Compatibility

Question
I recently aquired a Winchester 101 12ga.trap shotgun, serial # 103873 when was this made ?. It came with a single barrel but is chambered for O/U barrels. Where can I get just the O/U barrels for this model, so I can use one gun when shooting doubles , trap or skeet.                    Thanks George

Answer
Here is serial number reference link
http://www.midwestgunworks.com/merchant2/merchant.mvc?Screen=CTGY&Category_Code=...

Puts it as 1967.
I would contact Winchester
http://www.winchesterguns.com/products/catalog/category.asp?family=020C
Most break open guns require hand fitting of barrel.