Features/FAQs
Replacement countershaft cluster gear for matching early Muncie M21 close-ratio 4-speed manual transmissions. Used during transmission rebuilding to replace worn, chipped, or damaged gear teeth that can contribute to gear noise, whining, and rough operation. Designed for the early 7/8" countershaft pin configuration.
Fitment Applications:
- 1963–1965 GM passenger cars: equipped with a matching Muncie M21 close-ratio 4-speed transmission and 7/8" countershaft pin
Tooth Count: 27-22-19-17 Countershaft Pin Diameter: 7/8" / 0.875" / 22.225 mm Gearset Type: Close ratio — 2.20:1 first-gear transmission configuration OEM / Interchange Reference: 3831727, WT297-8, 304674, 5009087-1, 5009088-1
Compatibility depends on the installed gearset, tooth count, and countershaft size. Vehicle year alone does not establish fitment. Please verify casing and main shaft size prior to purchasing. GM switched to a 1 inch countershaft pin staring in 1966.
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