Not sure what is driving this belly mower

[Magnum]

Do you have a clutch and joint type shop nearby? They would be able to fix you up with the u-joints. Magnum, was yours set up like this one? I’ve never seen one of them.

I'll double check. But by memory I'd say yes , my memory is sometimes questionable so I'll take a pic

[Urbish]

Surplus Outlet is a good source for U-joints, but they're not as cheap as they used to be: https://www.surpluscenter.com/shop.axd/Search?keywords=universal+joint