The M20 and M21 have the same cut to the gears, the M22 is a straighter cut resulting in a greater strength. Since the M20 and M21 look the same one way to tell them apart (aside from the grooves on the input shaft) is the tooth count on …

The M22 Rock Crusher would come later to accommodate the heavy twist of Chevrolet's big-blocks in the mid-1960s. The M20 and M21 transmissions produced from 1963-'74 are easy to identify in both wide- and close-ratio units.

The M22 Rock Crusher would come later to accommodate the heavy twist of Chevrolet's big-blocks in the mid-1960s. The M20 and M21 transmissions produced from 1963-'74 are easy to identify in both wide- and close-ratio units.

M-22 "Rock Crusher" Identification. The M-22 close-ratio transmission is easily identified internally from the M-20 and M-21 versions by the angle of the gear teeth. The M-22 was only produced in a close-ratio version, so it will not appear on models with high rear-axle ratios (3.55 or lower numerically) unless someone has changed it.

M22 transmissions can only be identified removing the selector cover (side cover) and visually identifying the straight cut gears-all other muncie transmissions had conical cut (angle) gears. The most well known Muncie transmissions are the M20 (wide ratio), M21 (close ratio), and the M22 (rock crusher).

You can identify several unique signs that identify an M-22 "Rock Crusher," even if it does not have a GM hallmark imprinted on its surface. Step 1 Check the casting number, the production year and the gear ratios on the aluminum serial number plate attached to the transmission box.

M22 transmissions can only be identified removing the selector cover (side cover) and visually identifying the straight cut gears-all other muncie transmissions had conical cut (angle) gears. The most well known Muncie …

How to Identify Muncie 4 Speed Transmissions Identifying Muncie 4 Speeds III by Paul Cangialosi The most popular question has to be that everyone thinks they have the famous "rockcrusher" M22 4 speed.

The Muncie four-speed was produced in two ratios: the wide ratio (M20) and the close-ratio (M21). That being said, there was a second, close-ratio version (M22) that was developed to survive duty behind engines with a higher torque output, and was known as the "Rock Crusher."

The M22 Rock Crusher would come later to accommodate the heavy twist of Chevrolet's big-blocks in the mid-1960s. The M20 and M21 transmissions produced from 1963-'74 are easy to identify in both wide- and …

M-22 "Rock Crusher" Identification. The M-22 close-ratio transmission is easily identified internally from the M-20 and M-21 versions by the angle of the gear teeth. The M-22 was only produced in a close-ratio version, so it will not …

The M22 Rock Crusher would come later to accommodate the heavy twist of Chevrolet's big-blocks in the mid-1960s. The M20 and M21 transmissions produced from 1963-'74 are easy to identify in both wide- and …

M22: Known as the "Rock Crusher", designed for high-torque applications. Using these tips, you can confirm whether you have the right transmission for your Chevy and make …

M22: Known as the "Rock Crusher", designed for high-torque applications. Using these tips, you can confirm whether you have the right transmission for your Chevy and make informed decisions about any potential restorations or modifications.

Just three types of Muncie 4-speeds are available based on the RPO (regular production option) code used when a car was ordered: the M20 (standard wide-ratio), M21 (close-ratio), and M22 (heavy-duty close-ratio).

The M20 and M21 have the same cut to the gears, the M22 is a straighter cut resulting in a greater strength. Since the M20 and M21 look the same one way to tell them apart (aside from the grooves on the input shaft) is the tooth count on the cluster gear.