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Hey guys, got under to change tranny fluid today and I was looking forward to id’ing my tranny. I found some numbers but couldn’t locate the “A B or C” that is supposed to be there on the Muncie.
I snapped some photos that I’ll share, any advice is appreciated!
Hey guys, got under to change tranny fluid today and I was looking forward to id’ing my tranny. I found some numbers but couldn’t locate the “A B or C” that is supposed to be there on the Muncie.
I believe you have a pre-'69 Muncie – a '66 model year specifically.
The 3885010 is the case casting number from '65-'67.
The 3857584 is the tail-shaft housing from '66-'70.
The P1207 date sequencing pattern was used from '63-'66.
The only year you could have all three of these numbers on one transmission is 1966 model year. Pretty sure this one was built on December 7, 1965.
Unknown if this one is an M20 or M21. Production numbers for both '66 and '69 are pretty evenly split between the two. The only difference is internal gear changes. Which your car came with depends on the engine and standard rear gear but one could also order a non-standard rear axle or go against the recommended transmission. Here's a chart for which trans was standard for which '69 engine – you can see that the standard engine had to have the M20 and the L71 had to have the M21, but otherwise you could get either one for the other engines.
Here is a chart showing which rear axles were standard and optional for each engine:
69 Transmission Identification - 4 Speed
