For Sale: Genuine Muncie M21 4-Speed Factory Replacement Transmission – Dated 12/24/69

Up for sale is a GM factory service replacement Muncie M21 close-ratio 4-speed manual transmission — no VIN stamping, never factory-installed. This unit carries a late-1969 assembly date and features correct components from that production period.

Specifications:
• Transmission Type: Muncie M21 (close-ratio)
• Input Shaft: 10-spline with one circumferential groove
• Assembly Date Code: P9M24 → December 24, 1969
• Main Case Casting: 3925669 (used 1968–1970)
• Tail Housing Casting: 3857584GM (27-spline, short tail)
• Side Cover: 335308
• VIN Stamp: None (as expected with factory service units)

Condition:
Rebuilt in the mid-1990s by Kajun Enterprises, a known Muncie specialist, and has been stored in a climate-controlled environment ever since. View photos to evaluate condition for yourself. All major castings and identifiers are consistent with late-1969 Muncie production.

Also a potential option for the Oldsmobile owner who prefers the M21 over the M20, but wishes to remain visually and date correct.

Price: $2,800.00
Location: Nassau County, NY
Shipping/Pickup: Local Pickup Only

 

Update: The price on the Muncie M21 has been reduced.
New Price: $2,800 (was $3,800)

Details:

• Genuine GM factory service replacement Muncie M21 close-ratio 4-speed
• No VIN stamp (correct for service units)
• Assembly date code: P9M24 – December 24, 1969
• Main case casting: 3925669 (1968–1970)
• Tail housing casting: 3857584GM (27-spline, short tail)
• Rebuilt in the mid-1990s by Kajun Enterprises
• Stored in climate control since rebuild
• Never installed or run post-rebuild
• Ideal for 1970 Olds 442 W-30 with 3.91 or 4.33 gears

Location: Nassau County, NY
Local pickup only. I’m happy to help load it up.

Feel free to PM me with any questions or to arrange an inspection.

Thanks for looking!

 

Original ad posted in March already says 2800, 3800?

 

"Last edited by 442_No_More; Jun 26, 2025 at 10:34 PM."