If you or anyone with a case like yours lived in my region I would be glad to help and I am sure others would do the same. There are some of us like your step father and know we may leave a mess behind too.
A good auction company would help do this two but yours would be a low dollar sale based on what is pictured making it harder to find someone.
Tires need to be aired up, engines need to start, the tractor needs to be off the trailer, etc, etc. I have recently purchased a tractor and equipment trailer off of Craigslist so if you have time to deal with people that does work.
Did your step father have any close friends that knows this equipment. That would be helpful. I do not know the tractor but have the same generation F-700 truck except in gas.
Do you have other kinds of items so you could draw a larger crowd?
We just went thought this due to the death of my FIL and they just flat did not want to have people coming in and pick over things so having a sale may be bad advice.
OK I have gone back an looked picture by picture. There was a four wheel wagon, a couple small trailers and looked like one gooseneck and a LOT of stuff. The estate (your mother or who ever) really needs to have a sale as others have stated. There are things that would attract several bidders plus you know you got what the high bidder was willing to pay. The loader forks are attractive too.
The estate needs to get what it is worth.
Best of luck as you work through these matters.