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

So you can tell the difference by counting the teeth on the input or the cluster gear that engages the input. M21 input = 26 teeth. M20 input = 21 teeth. This is on a 66 to 74 model year Muncie.

Where is the casting code on a Muncie 4 speed transmission?

Many Muncie 4-speed maincases, extension housings, and sidecovers have a casting date code. On maincases, the code is usually found on the passenger side of the case below the casting number. The extension housing code is usually within a few inches of the casting number also on the passenger side.

Where is the extension housing code on a Muncie transmission?

The extension housing code is usually within a few inches of the casting number also on the passenger side. Muncie casting date codes are very different from other transmission manufacturers. The code consists of two circles, both 1/2-inch in diameter and divided in half. One circle is called the date marker, the other the status marker.

What was the tail housing on a Muncie car?

Casting # 3925661 was used in 1970 – 1974. The tail housing is casting # 3978764 and was used in 1970 – 1974. It has a passenger speedo location and 32 spline output.

What kind of shaft does a Muncie transmission use?

The Muncie utilized seven different input shafts. All transmissions with a 26-spline input shaft used a 32-spline output shaft, and all those with a 10-spline input shaft was paired with a 27-spline output shaft. Almost all Muncie transmissions were delivered with a groove (s) on the input shaft and counter gear.

What is the casting number on a Muncie 4 speed transmission?

The casting number 3925660 denotes this as a 1968 – 1970 Muncie with a 1-inch cluster shaft. In order to correctly identify a Muncie four-speed transmission, several visual clues are needed, and those cues involve the casting numbers on the case, side cover, and tailshaft.

Where is the extension code on a Muncie transmission?

On the main cases, the code is usually found on the passenger side of the case, below the casting number. The extension housing code is usually within a few inches of the casting number, also on the passenger side. Muncie casting date codes are very different from other transmission manufacturers.

Where are the casting numbers on a Saginaw transmission?

When properly identifying a Saginaw transmission, the casting numbers are a surefire way to know for certain what you’re looking at. These numbers can be found on the transmission case, and the first letter in this series of numbers is going to tell you exactly which Saginaw transmission you are looking at.

Where are the ring grooves on a Muncie transmission?

All original Muncie transmissions have ring grooves on the input shaft and counter gear. These grooves were put on for the Muncie assembly line workers to readily identify which input shaft to install and therefore shouldn’t be used for positive identification of tranmsissions since many of these shafts have been replaced.