How do I know if I have Muncie M20 or M21?

If you examine the 1966-’70 wide-ratio M20 input shaft, there are two grooves cut amid the 10 splines. From left to right are the three basic Muncie input shaft/countershaft combinations. On the left is the M20 countershaft and 10-spline input shaft. In the middle is the M21 countershaft and input shaft.

How do I identify a 4 speed Muncie transmission?

Another way to confirm that the transmission is original to your car is most Muncie four-speed transmissions will have a Vehicle Identification Number (VIN) number stamped on the main case. The engine and transmission were stamped at the same time by the final assembly plant.

What is a M20 transmission?

The Muncie M20 is basically a wide-ratio transmission and was intended for normal street driving use. The early ones had a 2.56:1 first gear. The later 1966-1974 units had a 2.52:1 first gear. They are compatible with a GM 3 Series differential. They are for economy and street drivability and just cruising.

What kind of transmission does a Muncie M20 have?

The principle of a transmission is the same. With the leverage and the gears combined with a lever action, you increase the power an engine makes. The Muncie M20 is basically a wide-ratio transmission and was intended for normal street driving use. The early ones had a 2.56:1 first gear.

What are the ratios of Muncie 4 speed transmissions?

Ratios of the M20 , M21 , M22 Year 1963-1965 Type: M20 Rings: None Ratio: 2.56 / 1.91 / 1.48 / 1.00 / 3.16 Year 1966-1974 Type: M20 Rings: Two Ratio: 2.52 / 1.88 / 1.46 / 1.00 / 3.11 Year 1963-1974 Type: M21 Rings: One Ratio: 2.20 / 1.64 / 1.28 / 1.00 / 2.27

Is the Muncie four speed called the rock crusher?

The M22 is called the Rock Crusher. “Dump the Rock Crusher,” hot rodders say. People think all Muncie four-speeds are Rock Crushers, but they’re not. Nowadays there are custom gear ratios and set ups, including M21 wide-ratio and M22 wide-ratio units.

What are the different types of Muncie hot rods?

One of the most common swaps involves a Muncie 4-speed. These are easy to adapt to a wide range of hot rods. There are three basic types of Muncies: M20, M21 and M22. A Muncie differs from a Saginaw transmission in that its reverse lever is in the tail housing, not the side cover.