Try e-gunparts.com
You can still buy stocks for the 336 from Marlin, or you can buy semi inletted stocks from Precision Gun Stocks, or Treebone Carving. You should also check Ebay, if you don't mind used stocks, as they are often for sale there.
i would first try numrich website at gunpartscorp. I would also try bobs gun shop in royal arkansas.They specialize in old marlin stocks..
model 55 the original marlin goose gun
Try Marlin Firearms Co., Numrich Gun Parts Corp., or Gun Parts at the link below.
Try e-gunparts.com, gun shops, gun shows, internet
Boyds gun stocks and I believe the marlin mod 80 will be compatible, if not then a bit of wood working will be needed to fit the action.
Marlin Fireamrs by Brophy.I can say that the Marlin model 55 shotgun was made from 1950-1965.The marlin model 55 goose gun which had a 36in barrel was made from 1962-1996.
Numrich Gun Parts Corp.should be able to help you.
I have parts for that model. sales@countrygunsmith.net
Gun shops, e-gunparts.com, gun shows, want ads, etc..
I would search at either Numrich gun parts corp.which can be found on the web,or Gun broker.com.under gun parts.
I would start my search at numrich gun parts corp.