The Story of the Mighty & Majestic Muncie 4 Speed …
The Muncie 4 Speed came in 3 basic models… the M-20, M-21 & M-22. The Muncie M20 was a wide-ratio transmission and was intended for basic street drive-ability and basically for cruising your car . ... The M22 was eventually dubbed the "Rock Crusher". It is a common misconception that all Muncie transmissions are "Rock Crushers", but ...