Mitsubishi ME21/24 engine
…they were built in. M stood for the Mizushima plant, E for engine, and 21 for being the 21st engine development by Mizushima, thus "ME21". When the 2G10 engine (a water-cooled version of the ME24) was introduced in late 1968, Mitsubishi's new unified naming convention had taken effect and thus its very…