4 Gear Trans Co

Parts and Gears to rebuild GM 4 Speeds

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4 Gear Trans Co

This page is dedicated to MUNCIE 4 Speed parts, gears and Main Cases for production from 1963 to 1974. There are six generations of Muncie 4 Speeds.

=1963 M20 & M21 10 Spline Input / 27 Spline Output and 7/8" Countershaft
=1964-65 M20 & M21 10 Spline Input / 27 Spline Output and 7/8" Countershaft
=1966-70 M20 & M21 10 Spline Input / 27 Spline Output with 1" Countershaft
=1971-74 M20 & M21 26 Spline Input / 32 Spline Output with 1" Countershaft
=1965-69 M22 Only 10 Spline Input / 27 Spline Output with 1" Countershaft
=1970-74 M22 Only 26 Spline Input / 32 Spline Output with 1" Countershaft

Email us at fourgeartrans@aol.com for prices, availability or questions.

MUNCIE REBUILD KITS:  Are Temporarily "Out of Stock"  
Quality parts from our inventory are assembled into kits for rebuilding Muncie 4 Speeds. These kits are available for immediate shipment world wide. Email us for assistance in selecting the correct kit for your application.

#297 1963 only M20 & M21 with 207 Input Bearing
#297A 1964-65 M20 & M21 with 307 Input Bearing
#297B 1966-70 M20 & M21 and 65-69 M22
#297C 1971-74 M20 & M21 and 70-74 M22

Rebuild Kits include the following items: Gasket Set; Shift Shaft Seals; Rear Tail Housing Seal and Bushing; Syncronizer Keys and Springs; Syncro Rings; Input Bearing; Main Support Bearing; Locknut; Countershaft; Small Parts Kit with Snap Rings, Thrust Washers, Needle Bearings and Taper Pin.


We have Old Stock and New Aftermarket Gears to replace your worn or broken Muncie 4 Speed gears. Email us with the information about the condition of your 4 Speed and we will help identify the parts needed, cost, freight and estimated delivery. Helpful information about your trans would be the Casting Number on the upper right side of the Main Case; if there are 10 or 26 Splines on the Input Gear (Clutch Gear); if there are 27 or 32 Splines on the Main Shaft into the Yoke; the casting number on the Tail Housing and Side Cover; and specifics about the problem your having with the trans.


We stock our own 4GTC Replacement M22 Gears. You can purchase them individually or in complete sets that include the 6 in-case gears (Cluster, Input, 1st, 2nd, 3rd and the Front Reverse Idler). The GM M22 gears came in Close Ratio (2.20) only. The Italian Aftermarket M22 gears come in Close (2.20) with 10 or 26 Spline Input (clutch gears) and Wide (2.56) in 10 or 26 Spline Input) Ratios. Our 4GTC  Private Label M22 Gears are available in Close Ratio (2.20) and Wide Ratio (2.52) with 10 or 26 Spline Input so you don't have to swap out your clutch installing the Wide Ratio M22 in you pre-1971 vehicle.  Please visit our "Specials" Page for introductory pricing on our "4GTC" M22 Gear Sets. Email us for pricing or with questions about your application. If you are ordering replacement gears for an M22 that you already have please provide us with the number of splines on the Input Shaft (into clutch) and the Output Shaft (into yoke).  Our private label 4GTC M22 gears are made with high nickel content steel, machined on CNC equipment and have a high standard of quality and endurance.  


We have complete "in-case" gear sets available for M20 and M21. We also have M22 Close and Wide Ratios as complete sets. These are helpful when you are changing from one ratio to another or from M21/M20 to M22.

Individual rebuild parts are available separate from the kits. Email us a list of the parts you need and we will respond with the cost of the parts and insured shipping.

We provide service/rebuild information for those customers that will remove original Muncie 4 Speed parts that are worn or damaged and install the new parts.  Or we have rebuilders across the country that we can direct you to for local service.