The power unit half of the S-5500/S-5500II pair that Sherwood sold as a separates system.
Valve receiver/unit: HT rails stay live after switch-off and the original can electrolytics must be reformed or replaced before power-up. Output transformers and the faceplate are the value drivers; history of a professional restoration usually adds more than it costs.
Marks that can be entered for this maker: Model / catalogue number, Model / catalogue number, British capacitor code (Hunts, Mullard), Japanese capacitor code (Nichicon, Chemi-Con, ELNA), EIA component code.
Nothing predates 1964; components only push the date later.
Sold-listing reading: fair $306, good $306, excellent $306 USD · 1 sold listings (thin sample — indicative only) · as of 2013-11 – 2013-11. Only 1 sold listing found in the reachable eBay SOLD table (https://classicreceivers.com/vintage-receiver-values) - below the 3-observation threshold, so this is an anchor, not a market average.
Evidence: Romero — Sherwood literature scans · Rubli.net — classic audio archive (values, ads)