This is an early Schroff & Ritzer Tele-Car ESC, released in 1980. This ESC was a reverse type ESC using a heavy-duty relay inside the aluminium case. Also two power transistors were used in parallel configuration for lower voltage drop and enhanced performance. The Tele-Car was one of the first ESC using such improved technology, other features were a BEC circuitry and a LED for indicating full throttle position.
Schroff & Ritzer based in Munich, Germany was one of the first manufacturers of electronic speed controls. They started business in 1971 making ESC for model boats. Early ESC like their Servonaut line were semi electronic devices controlled by a servo, also the powerstage was just replacing the MSC so unneeded voltage at halfway position was burned the same way. Real ESC with switching powerstage and not using a servo were introduced much later. Their Telenaut series was one of those newer units.
Classic RC 
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