Normally the pins and bushings are hardened high carbon steel. Any steel with enough carbon in it to harden will work. If the hydraulic cylinder rod end is worn the end can be replaced or bushed. Even some of the pre-hardened steels will work.
I’m going to make the pins out of automotive axle shaft.
I’ve got the pins made. Testing the original ones, they are harder than 65HRC according to the files. Do you think they are case hardened or through hardened? Should I through harden the pins I made? If so should I temper or leave hard? Also I don’t have a forge or oven so it’s hardened with a torch, it’s possible that the core could still end up a bit soft. The pins are just over an inch diameter.