numrich arms is a good place to go, sometimes they get original issue parts but mostly it's current production, they'll usually give you two different options if they have both available.
sarco may have them but I've heard bad things.
liberty tree collectors might have new production or original surplus but their prices can be a bit steep once you figure in shipping and such.
ignore my complete lack of capitalization. I still have no problem correcting your grammar.
I never said half the crap people said I did-Albert Einstein
You can't believe everything you read on the internet-Benjamin Franklin
Bean counters told me I couldn't fire a man for being in a wheelchair, did it anyway. Ramps are expensive.-Cave Johnson.