I have purchased a Sears rider model 917.25471 and I the operators manual it list a tiller attachment cultivates and prepares soil in one operation. Uses PTO from tractor, 12 counter-rotating blades break ground with upper-cut action, then deflects and retills it for a soft, aerated soil. Chain-Drive transmission. Tills 21-inch path, 6-inches deep. (Use chains and wheel weights). Stock No. 71-25246. Anybody ever seen one of these?