Missing or need repair? Reconditioning loader cylinders is simple. I recently dug a fork tip into the ground and blew out a curl cylinder. It would leak down over a few minutes. But repairing it was simple - I replaced the o-ring on its piston and the plastic spacer shims that center the o-ring in its groove. (same function as engine piston rings). The spacer had distorted and folded over onto the rubber o-ring, preventing it from sealing. Like-new performance restored for $5 ! If your piston rods are pitted you might have to live with minor dribble but I wouldn't replace cylinders that are intact no matter how bad they look. BushHog's price for new OEM cylinders is likely substantial and fitting something else is sure to be an adventure.
I don't think he will need to add those. The 'export' Yanmars (including his) have a
divider block to route fluid
out to the loader then back into the 3-point, in series between the pump and the 3-point. (
Outlet A in this diagram). But you are right regarding gray-market Yanmars originally built for the Japan internal market, optional parts are needed to get the loader in series.