You might try calling Simpson LTD in Galesburg, IL, as they are probably the biggest importer of used Husqvarnas.
First place I tried. They said they import only the rifles no parts stocks etc.
I kept looking on the internet found a listing on eBay from a picture contacted the seller and he had sold the one in the listing but gave me the name of a guy that had a 46 stock 2 actually one was cracked at the wrist one was in good shape. I purchased both one for my rifle one I’ll probably use for a pattern. Good luck with your search for the M640 stock.
