I simply took mine to the local hydraulic shop where they rebuilt them using standard parts. So that is the easiest option if you have the cylinders. They even straighten & replace rods.
Or that same hydraulic shop will also take a standard cylinder and adapt it to fit anything for not all that much money.
The hydraulic repair shop is less than a mile from the JD dealer - in fact there are three other Ag tractor dealerships in the same area.