The mono 75-watt partner of the MC275 - same circuit family, one channel per chassis.
Tube chassis: lethal B+ voltages remain after switch-off — discharge before service. Never power up an unrestored unit on original electrolytics. Serial tag is an ink stamp on a plastic label (often missing/faded); the value depends on original transformers (replaced/rewound iron cuts price sharply).
Marks that can be entered for this maker: Serial number, Model / catalogue number, British capacitor code (Hunts, Mullard), Japanese capacitor code (Nichicon, Chemi-Con, ELNA), EIA component code, Version & era marker.
Nothing predates 1961; components only push the date later.
Sold-price aggregates are not collected yet, so the archive gives no figure — condition, originality of the transformers and a documented recap move this model more than any list price.
Evidence: Roger Russell (ex-McIntosh) — McIntosh history · McIntosh Audio — historical index