JeffinPA (member here) makes driveshafts.......
Here is his ad.
I don't want to speak for Jeff, but he will probably need the specs off the old one, or need it physically, because the diesel shaft is different.
The flanges are still available from CC. This is the rear one......
Cub Cadet Parts.
Here is the front......
Cub Cadet Parts.
Or, you could do a driveshaft mod. Sam Mac here on the site can tell you how to build a CV shaft from a newer tractor to fit.......
Driveshaft Conversion.
Whatever you decide, we're here to help!!