Update.
Went to 5 or 6 different TSCs on two different trips across all of western NY, no tubes, other than buying the whole thing for $70+. Also managed to catch 2 tractor dealers open, no luck there either. I was ordering some other stuff from Agri Supply, so I chanced 5 bucks and ordered the Eurocardan tube, looks like a match! Better safe than sorry.
Went to 5 or 6 different TSCs on two different trips across all of western NY, no tubes, other than buying the whole thing for $70+. Also managed to catch 2 tractor dealers open, no luck there either. I was ordering some other stuff from Agri Supply, so I chanced 5 bucks and ordered the Eurocardan tube, looks like a match! Better safe than sorry.