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Tranny codes...what kind is it?

16K views 7 replies 6 participants last post by  1974grad 
#1 ·
Can someone help me with decoding the type of transmission I have?

4 speed.

Here are the numbers and location:

code location
3952659WB drivers side by clutch linkage
38575846M passenger side drive shaft enters

392566 US Patent 3088336 General Motors Corp P0524A..on passenger side midway on tranny

I was told it is a Muncie.

Thanks for your help
 
#3 ·
392566 -
i think thats the number you need. the big print one. there should be a zero at the end (after the 2nd 6). it is the same as mine...
which would be a 68-70 m20,m21,m22 case

P0524A

P-Muncie 4spd
0-is the year 1970
5-im guessing its the month, which is May. (most of them should have a letter for the 3rd digit, which would represent the month, like A for Jan. B for Feb, and so on).
24- 24th day of the month
A-m20 2.52:1 first gear, wide ratio

so all in all, its an M20 wide ration tranny, built on May 24th, 1970


aaron
 
#7 ·
Wide ratio vs close ratio relates to the spacing of the gears.
What that actually means in regards to driving is that there is not as much change in engine rpm between gears with a close ratio as there is with a wide ratio.
Generally speaking, the wide ratio is the more compatable tranny for a street dirven car that has a fairly high geared rearend, such as a 3.08, 3.31, 3.55. The close ratio is more compatable with a performance geared rearend such as a 3.70, 4.10, 4.56.
 
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