The Muncie four-speed transmission deserves more focused attention than it gets in most muscle car restoration discussions. The Muncie was Chevrolet's performance manual transmission from 1963 to 1974 and it came in two ratios: the wide-ratio M20 and the close-ratio M21 and M22.

The M22 Rock Crusher is the performance variant: helical-cut gear teeth like the M20 and M21 but with a wider face and stronger construction. The gear whine is the characteristic sound. A close-ratio gearbox with a differential suited to the ratio spacing transforms a muscle car's drivability — fewer rpm drops between shifts, more time in the power band.

Muncie transmissions can be identified by the case casting number and the date code. Correct-date transmissions add value to a numbers-matching car. Muncie rebuilds are well-supported by specialists.