I have a tow behind Ryan lawn aerator that has the same weight disks. So I can confirm you're correct. I didn't know Ryan made a 3 point aerator before. Having the disks rotate independently makes turning easier. The spoons are replaceable but not cheap.The green ones I think are Ryan brand aerators. The last 2 that I sold went to North Carolina. I had a couple of these too.
Around here farmers are using aerators in front of and behind liquid manure spreaders to aid in getting it into the soil instead of running off.