Since 1945, Muncie has delivered the muscle behind America’s most iconic transmissions. Today, the AutoGear Supercase continues that legacy—engineered for modern power with vintage soul.

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Muncie M20

The Wide-Ratio Street Classic

Smooth performance, ideal for street builds and cruising.

  • 1st Gear: 2.52:1
  • Input: 10 or 26 spline
  • Output: 27 or 32 spline
  • Known for: Larger 29-tooth countergear, 2 grooves on later inputs
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Muncie M22

“Rock Crusher”

Straight-cut gears, legendary strength. Born for big-blocks.

  • 1st Gear: 2.20:1
  • Input: 26 spline
  • Output: 32 spline
  • ID tip: No input grooves, 27-tooth countergear
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Muncie M23

Modernized Muscle

Smoother shifts, modern materials, and better RPM drop. Built for high-rpm launches, endurance, and performance upgrades.

    • Multiple ratio codes (Z, X, W)
    • SCCA-approved options
    • Supercase standard for added durability
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Assembly Matrix

Manual Transmission Gears Parts 2025

 

Detailed overview of assemblies, gear compatibility, spline types, and roller configurations.

Download the Assembly Matrix PDF

The Complete Guide

to AutoGear Gearbox & Gearset Option Codes

Ratio Code Guide

Instantly access input/output spline, roller, and ratio data for M20, M22, and M23 Series.

 

Download the Full Ratio & Code PDF

Getting you the right gearbox

Looking for a new Four-Speed or Muncie Gearset?

Our EZ Spec configuration form will help submit your inquiry for one of our gearsets.

EZ Spec Form

or send us a message

What Makes a Muncie a Muncie?

Model 1st Gear Input Spline Countershaft Teeth Known For
M20 2.52 10 or 26 29 or 25 Street-friendly, wide-ratio
M22 2.20 26 27 (straight-cut) Rock Crusher strength
M23 Variable 26 Various Modern refinement + Ultracase

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Testimonials

"Amazing…truly amazing. It is the more than I had hoped for and I could not be happier. Diane and I enjoy riding around and showing off the car."

Louis

"AutoGear did a great job in helping me decide the best gearbox for my ‘73 Camaro. It came in a week and it did just what Nate said it would do"

Customer

"I appreciate your honesty and integrity.  Sometimes as you well know things don't work out the way we would want them to. But we have pushed through and made things right. And again, I appreciate you working through this process, and Nathan too, can't forget about giving him props.  Very knowledgeable guy and an asset to Autogear."

Rick

"Conclusion of the race week end is quite good, we had issue with a slippery clutch.. so I already took contact with mike Norcia from Ram as you suggested to us."

Customer

"Me and my customer are very happy of your product,  we would like to thank you for the rapidity and the way you helped us to get ready in time."

Customer