I have a loader like yours on a 550. It is a Wagner Iron Works out of Milwaukee. I put new packings in one of the bucket cylinders a few years ago, I got them through Mc Master-Carr. I didn't have the piston out so not sure what it looks like. A local hydraulic shop has bulk rod, I would guess the piston is on with a nut, so it would be a matter of drilling and threading a new rod.

  Mel