In general, the packing in hydraulic cylinders is replaced without parts from the OEM manufacturer. Just disassemble the cylinders and take the whole lot of parts to a packing house and they can order exactly what you need for you. Working on hydraulic cylinders used to be a very scary and mystifying thing. Then I bought one just to learn on. Now I realize it actually isn't that hard.
I suggest you find Abom's videos on rebuilding hydraulic cylinders. I learned a ton from those.
metalmagpie