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Car Transmission Parts - Muncie M20 M21 M22

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6308N Ball Bearing 23MM Wide - Dodge Transmission Replacement Part 6308N Ball Bearing, 23MM Wide

6308N Ball Bearing, 23MM Wide

Our Price: $13.90

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Extension Housing Bushing 1.630 OD 35008 - FS5W71 Dodge Repair Part Extension Housing Bushing 1.630 OD, 35008

Extension Housing Bushing, 35008

Our Price: $3.99

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Extension Housing Bushing 2.010 Inch. OD WT297-62 - Transmission Parts Extension Housing Bushing 2.010 Inch. OD WT297-62

Extension Housing Bushing, WT297-62

Our Price: $5.89

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GM Speedo Housing Retaining Bracket and Bolt Kit, T5-TAB GM Speedo Housing Retaining Bracket and Bolt Kit, T5-TAB

GM Speedo Housing Retaining Bracket & Bolt Kit

Our Price: $11.90

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Input Bearing Output Bearing Max load, M6308N - Transmission Repair Parts Input Bearing Output Bearing Max load, M6308N

Bearing Max load, M6308N

Our Price: $39.77

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Muncie 1-2 3-4 Synchro Key & Spring Kit, WT297-K - Transmission Parts Muncie 1-2 3-4 Synchro Key & Spring Kit, WT297-K

Muncie 1-2 3-4 Synchro Key & Spring Kit, WT297-K

Our Price: $7.25

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Muncie 1-2 or 3-4 Shift Fork WT297-23 - Chevrolet Transmission Part Muncie 1-2 or 3-4 Shift Fork, WT297-23

Muncie 1-2 or 3-4 Shift Fork, WT297-23

Our Price: $24.10

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Muncie 1-2 Synchro Assembly, AWT297-80A - Transmission Repair Parts Muncie 1-2 Synchro Assembly, AWT297-80A

Muncie 1-2 Synchro Assembly, AWT297-80A

Our Price: $62.10
Muncie 1st Gear Bushing, 18-103-001 - Transmission Repair Parts Muncie 1st Gear Bushing, 18-103-001

Muncie 1st Gear Bushing, 18-103-001

Our Price: $27.95

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Muncie 3-4 Synchro Assembly, AWT297-2.5A - Transmission Repair Parts Muncie 3-4 Synchro Assembly, AWT297-2.5A

Muncie 3-4 Synchro Assembly, AWT297-2.5A

Our Price: $62.10

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Muncie 4 Speed Transmission Master Rebuild Kit - Max Load, BK116WS, Muncie Small Parts Muncie 4 Speed Transmission Master Rebuild Kit - Max Load, BK116WS-MASTER

Master Rebuild Kit

Muncie 4 Speed Transmission M20, M21 & M22 with 1" counter shaft bore.

High Performance Forged Synchronizer Rings made by Synchroking!

1-BK116WS - Master Rebuild Kit - Bearing, Seals, Gaskets with Synchronizer Rings

2-Key & Spring Kits

1- Set of French Locks

1-Counter Shaft Pin 1"

2-Extension Housing Bushings 27 Spline and 32 Spline Main Shafts

Our Price: $115.47

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Muncie Detent Ball Reverse 453593 - Small Chevrolet Transmission Part Muncie Detent Ball Reverse, 453593

Muncie Detent Ball, Reverse, 453593

Our Price: $4.01

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Muncie Detent Spring, Reverse, WT297-63 - Transmission Repair Parts Muncie Detent Spring, Reverse, WT297-63

Muncie Detent Spring, Reverse, WT297-63

Our Price: $6.90

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Muncie Drive Speedometer Gear 8 Tooth 1.41 ID, 1.84 OD fits 32 spline, 3978758 Muncie Drive Speedometer Gear 8 Tooth, 3978758

Muncie Drive Speedometer Gear 8T 32 spline, 3978758

Our Price: $16.41

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Muncie Drive Speedometer Gear 8 Tooth 1.18 ID, 1.84 OD, 3708144 Muncie Drive Speedometer Gear, 3708144

Muncie Drive Speedometer Gear 8T 1.18 ID, 1.84 OD, 3708144

Our Price: $22.90

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Muncie Drive Speedometer Gear 8 Tooth 1.18 ID, 1.76 OD, 3708145 Muncie Drive Speedometer Gear, 3708145

Muncie Drive Speedometer Gear 8T 1.18 ID, 1.76 OD, 3708145

Our Price: $16.41

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Muncie Extension Housing 32 Spline Main Shaft, 18-410-022 Muncie Extension Housing 32 Spline Main Shaft, 18-410-022

Muncie Extension Housing, 18-410-022

Our Price: $288.50

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Muncie Front Bearing Upgrade Kit, M6307NR, Spacer 4 Bolts with Gaskets, 18-410-025 Muncie Front Bearing Upgrade Kit M6307NR, 18-410-025

Muncie Front Bearing Upgrade Kit, 18-410-025

Our Price: $42.95

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Muncie Front Retainer French Locks Kit, WT297-F - Transmission Parts Muncie Front Retainer French Locks Kit, WT297-F

Muncie Front Retainer French Locks Kit, WT297-F

Our Price: $12.95

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Muncie Front Retainer, WT297-6 - Transmission Repair Parts Muncie Front Retainer, WT297-6

Muncie Front Retainer, WT297-6

Our Price: $22.98

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Muncie Gasket Set WT297-55 - Car Muncie 4 Speed Chevrolet Repair Part Muncie Gasket Set, WT297-55

Muncie Gasket Set, WT297-55

Our Price: $4.98

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Muncie Input Bearing Max Load, N1307L - Transmission Repair Parts Muncie Input Bearing Max Load, N1307L

Muncie Input Bearing, MaxLoad N1307L

Our Price: $67.95

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Muncie Input Bearing Slinger, WT191-45A - Transmission Repair Parts Muncie Input Bearing Slinger, WT191-45A

Muncie Input Bearing Slinger, WT191-45A

Our Price: $4.92

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Muncie Input Bearing, N307LOE - Transmission Repair Parts Muncie Input Bearing, N307LOE

Muncie Input Bearing, N307LOE

Our Price: $12.61

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Muncie Input Nut PR707A - Car Muncie 4 Speed Chevrolet Repair Part Muncie Input Nut, PR707A

Muncie Input Nut, PR707A

Our Price: $5.98

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Muncie Input Shaft 21T 10 Spline Wide Ratio, AWT297-16B Muncie Input Shaft 21T 10 Spline Wide Ratio, AWT297-16B

Muncie Input Shaft 21T 10 Spline Wide Ratio, AWT297-16B

Our Price: $99.80

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Muncie Input Shaft 21T 26 Spline Wide Ratio, AWT297-16C Muncie Input Shaft 21T 26 Spline Wide Ratio, AWT297-16C

Muncie Input Shaft 21T 26 Spline Wide Ratio, AWT297-16C

Our Price: $99.80

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Muncie Input Shaft 24T 10 Spline Wide Ratio,  AWT297-16A Muncie Input Shaft 24T 10 Spline Wide Ratio, AWT297-16A

Muncie Input Shaft 24T 10 Spline Wide Ratio,  AWT297-16A

Our Price: $99.80

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Muncie Input Shaft 26T 10 Spline Close Ratio AWT297-16 Muncie Input Shaft 26T 10 Spline Close Ratio AWT297-16

Muncie Input Shaft 26T 10 Spline Close Ratio, AWT297-16

Our Price: $99.80

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Muncie Input Shaft 26T 26 Spline Close Ratio, AWT297-16D Muncie Input Shaft 26T 26 Spline Close Ratio, AWT297-16D

Muncie Input Shaft 26T 26 Spline Close Ratio, AWT297-16D

Our Price: $104.60

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Chevrolet Muncie Transmission Parts - M20, M21, & M22

Muncie (General Motors) 4-speed longitudinal transmissions were developed in three distinct models – The Muncie M20 wide ratio manual transmission, the Muncie M21 close ratio manual transmission and the Muncie M22 heavy-duty close ratio manual transmission. Whichever of these three transmission types you're dealing with in your vehicle, you can expect to find a complete selection of Muncie M21 transmission parts, Muncie M22 parts and Muncie M20 parts, including Muncie M20 rebuild kits.

We have the best prices on Muncie 4 speed parts, including Chevy Muncie 4 speed transmission parts, and we can guarantee you a great selection of items extending from the lowest cost seal or bushing to a complete replacement wide ratio or close ratio M22 gear kit.

More Information on Muncie M20, M21 & M22 Transmissions

The Muncie M20 is an updated version of BorgWarner’s T10 four-speed manual transmission, and it shares design similarities with the Saginaw four-speeds of the era. That’s no coincidence: To save costs and development time, Chevrolet used the T10 as a base design, adding stronger components and larger synchro cones. This makes the M20 much stronger than the Saginaw or T10. The 4-speed Muncie came in three versions. Both the wide-ratio M20 and close-ratio M21 debuted in 1963 in the Corvette. The M22 “Rock Crusher” followed four years later. It uses stronger components to handle big-block power.

The original M20 was only offered for one year. It has the GM casting number “3831704” on the case. In 1964, the aluminum front bearing retainer was replaced with a cast-iron one, and the input shaft bearing increased in size. This version stayed in production until 1974. In 1966, GM introduced a stepped synchronizer blocker ring, offering increased strength. From 1971 onward, all transmissions used a 32-spline output shaft.

Contrary to popular belief, you cannot tell a 4-speed Muncie is an M22 by looking at the input shaft splines. All M22s use a 26-spline shaft made from a stronger alloy than the other 4-speeds. However, GM made both 10- and 26-spline versions of the M20 and M21. There are two ways you can tell the difference between the M21 and the Rock Crusher. The M22 has 27 teeth on the countershaft gear, while the M20 and M21 have 29 teeth. M20 transmissions have two grooves on the input shaft, M21 transmissions have one groove, and M22 transmissions have no grooves. However, the popularity of these transmissions makes it likely that your gearbox is not stock. Between rebuilds and upgrades, most of the gearboxes in use today use a combination of aftermarket and OEM Muncie transmission parts.

What makes the Rock Crusher so popular in street rods and drag cars? The M22 uses high-nickel-content-alloy straight-cut gears that have less of an angle than the M20 and M21 gears. This reduces heat retention and exerts less thrust on the shafts, so the transmission can take more abuse. This design creates the distinctive low-RPM rattle and high-RPM whine the Rock Crusher is known for. Gear ratios are the same as the close-ratio M21. The Muncie four-speed was used in a wide range of GM products through the 60s and 70s. However, the Rock Crusher was only equipped in cars that had high-performance big blocks, including the Corvette, Camaro, Firebird and Chevelle.

Thanks to the similarities between the M20, M21 and M22 transmissions, you can use a combination of Muncie 4-speed transmission parts to build the transmission you want for your project car. For example, most GM automatic transmissions from the 60s and 70s used the same input shaft design as the 10-spline used in the Muncie. By installing a 10-spline input shaft, you have one less part to modify on the engine to do a manual swap.

Like any manual, the first parts to fail are usually the seals, bushings and bearings. Of these parts, the front shaft bearing and rear seal are usually the first to go. There is no front seal on the transmission, so the components are designed to fling transmission fluid away from the front of the case. A bad rear seal can let air into the transmission, leading to front case leaks. Most synchro failure is caused by poor clutch adjustment. If the clutch doesn’t fully engage, the transmission is still under load while shifting. Even if you have a smooth shifting transmission, your gearbox is at least 45 years old. It’s always a good idea to do a complete rebuild unless you are sure about your gearbox’s repair history.