Jeff, this is about as rare as hens teeth Sir. I would check on large gun and accessory sites like (6)un (8)roker, Armslist and the For Sale sections of a few FN Forums as discontinued and hard to find firearms and accessories show up for sale by private individuals and small shops. Just replace (6) & (8) with G & B.

check with the major auction sites like G(un)B(broker) and G(uns)A(merica) Remove ()

Check gun stores, pawn shops, and as many web sites as you have time for. Check what you can daily. Someone will end up with one.