Anyone have a source for replacement stock set for a 39 straight stock in Walnut?

39A or the old 39 ?
If 39A check here...
http://www.boydsgunstocks.com/product.htm?pid=17971&cat=1227

that was going to be my suggestion.

I've been checking Boyds for some time now and they're out of stock.
Any other suggestions?

You can try here. Their fancy wood is pretty pricey, but they have reasonable prices on ordinary walnut from time to time.

http://www.shop.macongunstocks.com/main.sc

Did you look at Bob's Gun Shop?

http://www.gun-parts.com/marlinstocks/

Do you have the old/ broken stock?