6) 6-39. Operations Costing S. Lee Enterprises produces two models of lawn tractor: SL1 and SL2. The models are both priduced in the company's Louisville factory and go through identical assembly operations. The difference is in the quality (hence, cost) of the parts used. The following data are available for November, the latest month for which information is available: 6) 6-39. Operations Costing S. Lee Enterprises produces two models of lawn tractor: SL1 and SL2. The models are both priduced in the company's Louisville factory and go through identical assembly operations. The difference is in the quality (hence, cost) of the parts used. The following data are available for November, the latest month for which information is available