They are overpriced. That's why he still has them for sale. As far as being original ferguson I'm not sure about that. Always though that they were aftermarket. One set I had was stamp farmhand. They are cast steel and use a 10" square head bolt. I have had maybe 8/10 sets over the years, some flat tops like he has and some round tops. I have a set of flat tops on my '40 9n. They weigh in at 170 lbs each. I've never seen a flat top weigh more than that. The round tops can weigh 180/185 lbs. I've pulled them off Fords and Ferguson. The ones he has with fit the N series Ford or TO TE series Ferguson. They also made a flat top one that had a cutout for the later Ford hundred series model to go over the axle nuts because of the differences between the N series and the later models axle trumpets.
While installing the set on my 9n, now I know I'm getting old, I had to set up my Mason scaffold and use a come along and sling to get them on. Almost drop one on my foot one time.