Welder Dave, back in the 1950's a friend of mine in New Zealand owned one of these but rigged as a crane. They started life as a "Center-drive Speeder" by "Speeder Machinery Co". but when they joined up with "Link-Belt" that design was sold off to Sergeant. Power was an IH TD9 engine, petrol start but the center drive sprocket was the weak point. If you tightened up the track chains to stop it jumping the sprocket, the tracks would bind and stall the engine so my mate had an old D4 on hand to drag it around the yard otherwise it was quite a good little machine, conventional controls and would have been good mounted on a truck chassis. That bucket is a bit more than "perforated" and as you said, probably made for reclaiming bigger river stone for a crusher.
