I finally was able to finish my 1983 JD 420 Hydraulic system over-haul. New pistons, new lines, new filter and new fluid. The old fluid was almost black it was so old. This was my first time messing with hydraulics, but in the end there were no more leaks, so I'm happy.
The Innovative Grapple I got last winter was a bit tricky to install due to receiving no instructions, but I figured it out eventually. The new pistons I got were bare metal so I painted them JD green before installing.
Then it was time to test it out at our place in the middle of the VT woods. It worked like a charm.
I'm a happy man!