I would go to E-gun parts.com.
Try Marlin Firearms Co., Numrich Gun Parts Corp., or Gun Parts at the link below.
numrich's gun parts has a fair selection of new and used parts for that firearm... http://www.gun-parts.com/marlin/
numrich gun parts at e-gunparts.com!
Try Numrich gun parts corp.
Which model??
I have a Marlin Firearms Co. 12 gage, bolt action shotgun.
I believe it was a Marlin model 49. I had one of these myself in the 60's. If you are trying to find replacement parts, then you can use the Marlin parts as is. That is what I did, parts for Marlin are easier to find and sometimes cheaper.
I believe that they were made by Thompson Center for Marlin. I have no idea as to how many but I can say that it is hard to find parts for them. Some parts are compatible with the Thompson Center Muzzleloaders but I can't find a reference right now.
Numrich Gun Parts Corporation is a good online source.
Marlin sells parts for these rifles as does Numrich. Marlin at - www.marlinfirearms.com Numrich at - http://www.e-gunparts.com/model.asp?idDept=158
Try contacting Marlin parts. Consumer Parts Orders: Consumer Service Dept: (800)544-8892
Try e-gunparts.com and Marlin