Please note that this lot will need to be collected in Chobham, U.K.

At a time when the price of a standard Mercedes-Benz SL 600 was just 5% less than a Rolls-Royce Silver Spirit, it is unsurprising that the SL70 always was an extremely rare car; the engine upgrade alone cost roughly the equivalent of € 50,000.

Nevertheless, the reward was staggering: a hand-built 7.1-liter AMG-tuned version of the exquisite M120 V-12 engine, producing a supercar-slaying 489 hp.

As with all SL 70 examples, this Azurite Blue Metallic over grey chassis began life as an SL 600 for the Japanese market and was completed in January of 1996.

Records paired to the affixed AMG Japan commission plate indicates that the SL 70 conversion was begun on February 13 and completed on May 20, 1996.

Additionally, accompanying documentation confirms that this rarified chassis also received the ‘E70 Power Pack’—which uses an engine management computer borrowed from the contemporaneous S72 AMG to achieve a conservative...