Another dumb idea...

That's easy I would



Then bore a hole in the axle drive flange of the bus axle for the dana 70 shaft to fit in then weld them together. The machine shop I used to work for builds pto shafts and complete units for all kinds of stuff. It would be a piece of cake.

ummmm that would brake the shafts are hardend and made out of ductal iron

Axle shafts are machined all the time.