Don't have them in front of me at the moment, but I doubt a C series sprocket will fit a Super XL. If you want 404 on it, its pretty easy to find center drive sprockets with a replaceable rim, so you can use 3/8 or 404, just swap the rims out. Sprockets are all over the place for less than $20 and rims are usually around $3 - $4 each. I'm not sure running 404 on a Super XL is a good idea though. Its gonna put a good bit of extra load on the saw, and Super XLs aren't that big.
Dan