I have no idea, since I've never carried a revolver or even owned one.
I would suspect that you won't find that model listed on Galco's website as a holster specifically made for it. But, most revolvers have close to the same dimensions. Find out if it is comparible to a "J" or "K" frame, etc. Then, maybe you can take it into a shop, and they will let you try a few holsters.
Uncle Mikes makes some generic holster sthat will probably work, but they are nylon.
If you are looking for a "cowboy" holster it appears the Marshall has the same frame as the Stampede and I purchased one for my stampede from Midway made by Oklahoma Leather that was cheap ($27) but servicable. I am cheap and couldn't see spending a fortune for something I might never use. (I'm thinking of Cowboy Action but haven't tried it) Belts are dear as well and I purchased an Oklahoma with cartridge loops. I read on another site that belts made for tool-belts by an outfit called, I believe, Kent are wide and serviceable and cheap (about $20.00). I have one for my tool belt that came from Home Depot some time ago (unknown brand) that has basket weave but the wrong color -too light to match Oklahoma products. If you can get one in brown or are a handy person who can dye the belt you could get away for less. Oklahoma also makes a 1 3/4 inch plain belt with no loops for about $17-$18 that might be a little skinny but would probably match and be suitable foe someone with a smaller frame. Stampedes are usually not listed in the catalogs I have but it appears holsters made for Colts and Vaqueros will fit but most holsters are designed for 4 3/4 inch barrels so for 3 1/2 might be a little long. The older Vaqueros had a larger cylinder than the newest one so one made to fit it should asssure a reasonable fit. If cost is no object the sky is the limit.
El Paso Saddlery makes some of the finest holsters (and especially revolver holsters) I've ever owned. The company dates back to the 1890's, and makes both modern and old west type holsters. You can check them out on-line. You may have to wait a while for a holster from EPS, but it will be more than worth the cost and wait.