Case made a 38" wide, single stage snow thrower specifically for the 200 series tractors built from 1971 to the end of the series in the early 90's. There is also a 48" wide version that was built for the 400 series tractors but it will fit the 200's with no modifications. Case did not recommend the wider model for 200's with less than 14 hp but I have heard from several 12 hp owners that they have no problems spinning the wider unit.
Over the years, minor changes were made to both models and as these changes came about, the first letter in the model number advanced from J-38 to K-38 to L, M, N etc.
There was also a kit available for the 38" model that widened the overall cut by adding "wings" on each side of the housing so if you happen to come across one that has these wings on it, you'll know that it isn't some weird model.
The latest offerings from Ingersoll begin with the letters SB, as in SB48 or SB38 and while they'll fit on your machine, they won't work. In the early 90's, Ingersoll turned the engines around 180 degrees and that move meant that the crankshaft rotated the opposite direction for the purposes of the power take-off. Ingersoll had to redesign the mule drive for the blowers so that they would spin correctly. And the traditional left discharge mower decks became right hand discharge decks. They too, still fit on the old tractors but won't work.
Used SnoCasters show up on e-Bay all the time and you can expect to pay up to $400.00 for something decent. Just make sure that it's complete with the chute crank handle and the L-arm that attaches to the lift bracket on your tractor and also supports the chute crank.
Too bad you're not in southern Ontario because I could sell you either model. LOL
Don't use anything but OEM drive belts. You can buy them on-line from Ed at the link below. Craigslist and Kijiji are two local places to watch for used ones or even advertise on for free.