I have a '50 model 4100 that sat up for almost 40 years. Long enough for ALL the oil in the SM420 to leak out through a leaky PTO shaft. Then it proceeded to rust and actually got stuck. First manual transmission I ever saw get stuck. I was able to free it up, flush it out and put new oil in it and it still works fine. lol It's not even noisy.

1950 4100 - unrestored and driven weekly for almost no reason at all.