Just a small point:-
DO NOT USE EN1A!!!
Sorry to shout, but it rusts as soon as you look at it indoors. On a tractor it will be a mess within the week outdoors, if it isn’t completely sealed. The leaded version is worse, but the re-sulfurized version is also prone to corrosion.
EN8, unhardened is good for most uses. EN16T is better if higher strength is needed.