D operates an automobile repair garage. P brought a car to D's garage for repairs. It was necessary to remove the engine from the car. The engine was removed and D stored the car in an unfenced area between the garage and an adjacent street. Just by coincidence, its transmission disappeared. D told P that the transmission had been stolen. Exactly when and by whom the transmission was removed are facts which remain unknown. P demanded reimbursement. D disclaimed any obligation to compensate P. P sued D for conversion and, in the alternative, for negligence. The lost transmission had a reasonable market value of five hundred dollars. D admitted its status as 'bailee' of the P's automobile. In its defense at trial, D introduced testimony as to the currently prevailing custom and usage regularly observed by other service garages in the area. After a nonjury trial, the court entered judgment in favor of the D. P appealed. P contends initially that the court erred in admitting the customary evidence because the customary practices of the Pocatello garage owners constitute negligence as a matter of law and a deliberate disregard of a known high risk of theft.