1963 T-10 vs. Muncie M21, when and why did GM switch?

Tom Miller

Well Known Member
A friend of mine that rebuilds transmissions(Vintage Powertrain) in Saline Michigan, called me this morning and asked me if I knew when or why Chevy went to the Muncie?
The only reason that came to my mind is that I believe GM owned Muncie, whereas they were "sourcing" 4 speeds from Borg Warner, so it was probably cheaper to go with their own Muncie trans.
I believe I read somewhere that at some point during 1963 production, the trans vendor switch happened?
My friend Brian has a September 62 T-10, so this points to early model year production.
He has found that this particular trans has some 1963 only features/components such as, small 4 1/4 bearing support/register which would need a bell housing with smaller than the typical 4 5/8 I believe is the more common size.
There are also some different bearing sizes inside, and bearing retainers, etc. that are different for 63 only.
His other question was, did they switch for vendor reasons, or did the High Perf solid lifter & Z11 cars get the T-10, and lower perf(340hp409's & 327's) get the Muncie??
Also, the trans he has is cast " High Perf", and has a cast bowtie on tail housing. There are also a couple more stampings on it, and maybe a partial vin?

Thanks guys
 
Last edited:

real61ss

Well Known Member
Supporting Member 8
I believe that somewhere i have a copy of a letter dated late Feb of 1963 (I believe it was 20 something, going off memory here) stating that the Baltimore plant had recieved its first shipment of Muncie transmission's
 

Tom Miller

Well Known Member
So to answer my question, you're saying first part of 63....ANY chevy ordered with a 4 speed would have receive a T-10, correct?
The trans I described above is nothing special then.
 

Carmine

Well Known Member
Supporting Member 10
Hate to throw a monkey wrench into this thread, but my '62 has a T-10 that I believe was built in '61. I don't recall the numbers right now. It also has a cast iron main body and an aluminum tail shaft. I wondered why they did this and it was mentioned that they were trying to use up all the old parts and eventually go to all aluminum cases. Guess that makes sense. I don't really know, Carmine.
 

real61ss

Well Known Member
Supporting Member 8
Carmine,
That probably is a 61 or earlier transmission, for sure isnt the original transmission. All of the 61 transmissions had cast iron main cases except for the few 409 cars and the Corvettes. 62 had aluminium main cases
 

Carmine

Well Known Member
Supporting Member 10
OK. I often wondered why the case and tail weren't of the same material, Carmine.
 
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