If you purchased it new you should get support from Marlin with the 5 year warranty.

 

Don't see any reason for any Marlin stock to go any other Marlin, except maybe the 39. Marlin shouldn't have changed the receiver because of a laminated stock, birch, walnut or any other flavor. Regarding the straight stock though....if you change the stock and nothing else you will have a curved lower and a curved lever. Both can be made into a straight stock configuration, you can find info in the Reference Forum about 2/3 ways down the index. Or you can try and swap with another member here, either that or buy the parts.

 

Straight stock to straight stock should work. If you change and go to pistol grip you will have to change some parts.

 

I'd try gluing the stock before I bought a replacement. Can you post pictures of the crack? I've repaired a couple and you had to look hard to find the repair.

 

I'm with "biggog", repair it. I've glued two of them, both 1894's, one a friends, and one is one of my favorite shooters.
Discovered them both the same way you did...loose stock with all screws very tight. Spread the crack with a small screwdriver
then squeezed in some urethane glue. Both done 9 or 10 years ago, and had forgotten about them until reading your post.
Can't see the crack on either gun, too this day, and both guns are shot regularly!

 

Thanks I will try this first. Thanks also to all who responded.