Muncie M21 and M22
Muncie 4 speed transmissions were used in General Motors cars from 1963 to early 1975. It was actually based on the T10 design and uses the same basic gear layout. The T10 made its appearance in GM cars in 1957. From 1957 to 1963 many changes took place inside the gearbox to meet the increasing horsepower the new engines were putting out. It was replaced by the Muncie in late 1963. The Muncie 4 speed was used in production vehicles until power levels dropped in 1975. This was the first year catalytic converters, smog pumps, and low horsepower were introduced. These new requirements led to the demise of the Muncie and the reintroduction of the improved T10 called the Super T10. The Muncie was used with most performance engines, and is not to be confused with the Saginaw or Borg Warner 4 speeds.
The Muncie is distinguished from the Saginaw in that the reverse lever on the Muncie is mounted in the extension housing, whereas the Saginaw reverse lever is mounted in the side cover. The main difference between the Muncie and the Borg-Warner is that the Muncie has a 7-bolt side cover and the Borg Warner has a 9-bolt side cover.
The M21, M22 transmission adapters we manufacture will normally require the installation of a new output shaft .
When ordering Muncie adapters you will also need to consider a Hurst shifter, shifter bracket, and shifter rod kit. We now offer new transmissions with our adapter kit installed.
Forward Speeds .... 4
Dates Produced .... 1964 - 1975
Manufacturer .... Muncie
Case Length .... 10.50
Stock Adapter Length .... Intergral
Bellhousing Length ... 6.50
Over All Length .... 17.00
Case Material ... Aluminum
Input Shaft Spline .... 1-1/8 10 & 28 spline
Length .... 6.50
Pilot Diameter .... .590
Length .... 1.00
Output Shaft Spline .... 27
1st Gear Ratio .... 2.20
2nd Gear Ratio .... 1.64
3rd Gear Ratio .... 1.28
4th Gear Ratio .... 1.0
Transmission Weight .... 100