The original muffler is made by Nelson Global Products. They are still in business world wide.Their web site has an application pdf file for small engine exhaust solutions. With the similiar stlye exhaust mufflers. On EBAY "Nelson Muffler" there is for sale, new mufflers. And they ship to Canada. But not cheap.
One Nelson Muffler lists for $86.01 and is type #14490t type 8 garden tractor horizontal muffler, currently for sale. Looks like they are still available. Please note,
I did not measure and compare the old muffler to the new EBAY item.