Painting the articulating links would be optional. I painted them when I restored my '50 COE but they are no doubt covered in brake dust by now. I will say the truck spent most of its life outside and there was only a bit of surface rust when I intervened. Clean them up and you will be good to go.
Kent

1937 Chevy 1/2 ton
1942 Chevy 1/2 ton
1947 Diamond T Model 509
1951 Chevy 1/2 ton
1950 Chevy COE Model 5700 ~ "Barney" ~ And more pix