1974 Muncie M21

Discussion in 'VIN, Trim Tag & Drivetrain Decoding' started by RLP, May 18, 2020.

  1. CamaroNmotion

    CamaroNmotion Veteran Member

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    There were NO muncie transmissions of any type built in 1974. Production ended in 1973 and the transmissions were saved for Vette's, Z28's and TransAms. Switch to Borg Warner was stated in a GM letter in Jan 74, however there were Muncie's left over and used up till late Feb or early March 1974. My original 74 Z28 02B came with M20 muncie. Something I noticed from your photo stamping has the vin and date code stamped together on one side of the transmission, mine has vin one side and date code on other side. And whats with the xxxxxxx, never saw that. Your transmission is a re-stamp...and a bad one at that.
     
  2. RLP

    RLP New Member

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  3. RLP

    RLP New Member

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    I posted this on another forum and amazingly a guy posted pics of his 74 z/28 M21 with xxxxx on his also. His M21 was dated the day after mine. P4R24B. He says these were late installs and restamped. His was an 03C car vin# 197xxx later than mine. His vin/date code were also on same side. Maybe yours was opposite because you have an M20?
     
    Last edited: May 21, 2020
  4. RLP

    RLP New Member

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    I thank everyone who responded to this thread. I will be selling this 74 z/28 M21 in the near future after I pull it from the current vehicle and will share the link here if anyone is interested. I wanted to get the correct info and try and find out if this z/28 is still running the roads and offer current owner the M21.
     
  5. RLP

    RLP New Member

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  6. Jonesy

    Jonesy Veteran Member

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    I already answered this in another forum he posted in.
    Its not a restamp. My original 33,000 mile 74 z/28's M21 was built a day after this one. It is also XXXX'd out like his. My car was built 03C with M21 trans.
    4N179503 is my VIN. It was stamped 3 times on this case. This transmission is definately the original one to my car

    Heres a pic of my trans stamping. These M21's must have been laying around and were used up as needed.

    IMG_0982.jpg

    IMG_0908-1.jpg
     
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  7. Jonesy

    Jonesy Veteran Member

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    To clarify, I said the M21 was used after Jan 74 and that the XXXX were the way the factory deleted a mistake stamping. Heres more pics of my tranny shows 73 date marks on components. 3925661 case, 3978764 tail shaft, 335308 side cover. Has TCS switch and Stewart Warner speedo reducer. You can see a big ink 3 on top of the case in black ink. Also has a W ink stamping on it.


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    Last edited: May 27, 2020
  8. Jonesy

    Jonesy Veteran Member

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    IMG_0989.jpg IMG_0983.jpg IMG_0984.jpg IMG_0991.jpg
     
  9. Jonesy

    Jonesy Veteran Member

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  10. BigBlock73

    BigBlock73 Veteran Member Lifetime Gold Member

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    Might be 72 strike leftovers
    My 73 had a 307 that was restamped at the factory
     

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