We had seveal 5020 running gears. They were rated as 8 ton wagons, I believe. The 5010 would be a bit lighter. I think they  were rated as 6 ton wagons. I believe they were manufactured by Electric Wheel. If they aren't all beat up they should make you decent running gears. We've had ours since the late 60's-early 70's. Ours have seen some hard use and are getting pretty beat up.