(14 customer reviews)

Muncie Super Duty M23 Upgraded Ultra Case 4-speed Road or Drag Racing Rock-Crusher. SALE EXTENDED!!!

$ 3,549.00

Severe Duty M23 gearboxes feature Upgraded Ultra Case with enlarged Front and Rear steel ‘thrust button’ case assembled modular counter shaft clusters with ground drive gears, unit cage needle bearings, integral counter shaft spacer tubes and carbonitrided over sized synchronized hubs. Slick Shift 18 spline hardened sliders. Small pad Crowned Steel Forks. Welded Shift Shafts. Forged Brass blocker rings. Main drive oil seal input shaft and bearing retainer. 34 tooth 1st super strong 1st gear (stronger that the M22 1st gear). C355 Forged Aluminum mid plate. Lightened main shaft for less rotating mass. The M23 is the strongest Muncie style 4-speed available.

Lead time 4-6 weeks. 20% Fee on Cancellation of order after 45 days.

SPECIAL RUNS THIS WEEK. CALL JEFF (262)893-9812 for details.


Complete gear polishing available for road racing and serious competition;





14 reviews for Muncie Super Duty M23 Upgraded Ultra Case 4-speed Road or Drag Racing Rock-Crusher. SALE EXTENDED!!!

  1. louis carbone

    have one in my 64 tempest 480 inch Pontiac shifts great great sound exel service

  2. Paul Miller

    I just got my m23z for my 1970 Gto and the transmission is amazing. I can’t say enough good things about Jeff and this transmission. Excellent customer service and extremely knowledgeable. He spent over a hour just answering my question and never pressured me buy. I will be a repeat customer for sure

  3. Paul Miller

    I just got the m23z in my 70 GTO and I can’t say enough about the transmission. Jeff is very knowledgeable and extremely helpful. I will be back for more transmission.

  4. Shawn Riley

    Recently installed this Midwest Muncie M23 in my 72 Buick Skylark with a 462 big block. Very nicely built piece with positive shifts. The gear ratios as spec’d by Jeff are perfect for my rear end gearing/tire size combination. No more worries about breaking that old stock cased Muncie with sticky tires!!! Had a bit of a lead time, but worth the wait. If a transmission builder is that busy, there’s a reason for it…

  5. Dave

    Ordered my M23 in November and can’t wait to hook up between a ZZ502 and a new 9″Ford rear end. I hope she whines and whines sweet music all day long, no radio needed!
    Ordering was a breeze with Jeff

  6. Cole

    Recently ordered my M23 Jeff was a very nice person to talk to told him exactly what I had and what I like to do in my 68 Chevelle with a zz502 told me exactly what he was going to do I can hardly wait my M21 did not last a thousand miles????
    I am an old guy and love smokers slamming gears hard !!????

  7. Barry Underdahl

    Jeff is great to work with. When you call he answers the phone. I called with many questions about his M23 Super Case including bolting on a Gear Vendors overdrive. Jeff really knows his stuff and recommended the proper ratios for my project.
    I especially liked the fact that his M23 won’t get hot on a road course even without
    an external cooler and for a transmission that handles real power the price ain’t bad either.
    I ordered the GV overdrive and had the housing sent directly to Midwest Muncie.
    I am very happy with how cool it is and the obvious attention to detail and quality
    Jeff puts into his Muncie. I can’t wait to get my ’66 Chevelle on the road and on the track!

  8. Jeff Collins (verified owner)

    My new M23 Super Duty is PERFECT! Jeff, you REALLY came through and I could not be happier with this new transmission and all the personal, technical help you provided me! ALL of your help and technical guidance you provided me with how we should set up the gearing ratios just turned out awesome, and I finally luv running this hot rod through the gears with this M23! And ALL your recommendations for the new clutch assy, mounts/brackets for reverse lights, QuickTime bell housing, Hurst shifter – and your personalized technical support are so greatly appreciated …. the results are phenomenal! The transmission performs and shifts PERFECTLY! Finally no more grinding issues shifting from 2-3 like I had with my TKO 600!! Thank you again Jeff, I could not be more pleased with my M23 and every expectation that I had was exceeded – thanks to you! Rob Burchett

  9. mark munster

    Thanks Jeff! I replaced the over worked blown up M20 in my 1969/427 Corvette with a Midwest M23 super duty. It fit perfectly, shifts and runs so much smoother than before. Working with Jeff was great he had my transmission built and shipped in 7 days. I recommend Midwest transmissions to all my classic cars buddies and friends.

  10. Dave

    After a summer of using my M23 I’m really happy, it sounds amazing and shifts like silk. Great product and support from Midwest. Thanks

  11. steve cooke

    Got my M23 last summer from Jeff , no problems trans went in prefect. Don’t expect a trans like this to shift smooth untill it breaks in. took about 400 miles to get there. Thanks Jeff. steve, Chicago

  12. Joe Gio

    Jeff always picks up the phone and never tries to rush you off. Just got my M23Z as promised in a nicely packed crate.
    Supply chain problems slowed things down a bit but Jeff came thru.
    Thanks again,
    Joe from Jersey. 69 Firebird 455, 4-spd, 3.42, 6-71

  13. William Reehil (verified owner)

    Jeff is the man, built my M 23Z strong, standing up to a fairly stout 565 inch BBC no sweat, and it’s got that rockcrusher whine that we all love, can’t get that with a TKX! Really this guy knows his stuff, trans shifts great, love it. Thanks Again Jeff!

  14. Ricky Fitts

    Just wanted to give Jeff a big thanks for working with me on my project ,our time-line matched up great when I got to the point of the build where I needed the transmission he got it right out to me, Thanks Jeff for keeping us all going and having fun I really hope you are passing the trade on to the next generation we need more good builders to help us keep doing what we love to doing

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