1974 Muncie M21

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

  1. RLP

    RLP New Member

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    I recently bought a project car 1975 TR7 heavily modified with small block and what was supposed to be an M22 trans. After taking pics of trans and decoding I found out it's a 1974 M21. Research is confusing at least. Date code P4R23B. 1974 M21 October 23rd? Serial vin 14N192910. Late Camaro production with M21 ?
    Other #'s coincide with 1970-74 M21, case #, side cover,and tailshaft.
    Could this be the last camaro produced with the M21?
     

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  2. Gary S

    Gary S Administrator Lifetime Gold Member

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    It could be. I don't believe there was any documention anywhere as to when the switch was made from the Muncies to the Borg Warners.
     
  3. COPO

    COPO Veteran Member Lifetime Gold Member

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    4 speed close ratio tranny’s on all 2nd Gen’s to 1981 we’re RPO code M21. Muncie has 7 bolts on the side cover and Borg has 9. The ‘74 should have a 3925661 main case and a 32 spline tail 3978764 and 1 groove on the input shaft. Date code P for Muncie and W for Borg.
     
    Last edited: May 19, 2020
  4. Gary S

    Gary S Administrator Lifetime Gold Member

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    The tranny number (P4R23B) follows the Muncie sequence, so likely it is a Muncie. I don't know what stamping sequence was used on the Borg Warner, but likely GM might have used a different code. The "P" was the identifying code for Muncie all years it was offered.
     
  5. COPO

    COPO Veteran Member Lifetime Gold Member

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    You talk about a TR7 with a Muncie then ask, could this be the last Muncie in a Camaro? Huh? I’m lost.
     
    Last edited: May 19, 2020
  6. crashent

    crashent Veteran Member

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    P4R23B was built Oct. 23rd 1973 ...
    Remember Muncie build codes go by model year, Oct. of 1973 the 1974 model year cars are being produced...

    Hope this helps... Crash
     
  7. RLP

    RLP New Member

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    You are correct on the numbers. I believe from research I've done that after 74 Borg Warner produced the super T10 that replaced the Muncie m-21 from 1975 to 1983. And certain Corvettes from 84 to 88.
     
  8. RLP

    RLP New Member

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    This is the 1975 TR7 I am referring to. This car was built by a friend of mine who passed and I purchased the car from his daughter. It is basically a race chassis 9-inch Ford coilovers tubular a arms full roll cage small block Chevy backed by a Muncie M21. I am removing this engine and transmission combo and replacing with an LS engine with automatic transmission for Street drivability. Ford 9-inch with 389 gears would not be good for Highway cruising. I am probably going to sell this transmission. Although the 74 Camaro is not as sought-after as first gen Camaros I thought maybe you guys would have information on it. I have owned two first generation Camaros.
     

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  9. RLP

    RLP New Member

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    Thanks I am replacing this transmission and what to get the right information on it before I sell it.
     
  10. Ricks72Z28

    Ricks72Z28 Veteran Member Lifetime Gold Member

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    The Muncie is for an early built 74 vin 02910, I’m sure someone on this site needs one for a 74 car...
     

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