Have found a muncie transmission that I'm interested in purchasing for my '67 Vert. I know it's a m-20, but having trouble year and what it came out of.

Here are the #'s

Side Cover:# 3884685
Case :# 3885010
Tail Section:# 3857584
Bearing Cover:# 3851328

Has # A172787 & PO531 stamped on main case.

There is also a metal tag attached to the side #'s are as follows: 3870357

This Transmission has recently been rebuilt and I can get for $275.00...is that a good deal?

$275 is a steal for a functional unit, cores go for 300-400.00

Found on Google.
Serial numbers for Muncie 4 speeds always begin with the letter "P". P stands for Muncie. Why.... I have no idea. The serial number is a date code the transmission was built for a particular year. Serial numbers from 1963 to 1966 included only the month and day. P0101 would indicate January 1st. From 1967 to 1968 the serial number got a year designator and a letter designator for the month such as P8A01, meaning January 1st 1968. One important point is that if you have a Muncie dated with a December build date it was actually built the prior year. An example would be the date code P8T13. This is for a 1968 production car. The T stands for December and 13 is the day. To confirm this simply look at the VIN number. It will usually begin with a 18S101350 or a 28N12950. This means the Muncie was assembled December 13, 1967 for the 1968 model year. The VIN number will usually be a low number. 1969 to 1974 Muncies got a ratio designator at the end of the serial number. An example would be P4D23B. This equates to April 23, 1974, M21 ratio.

Month Code Chart

January Letter: A May Letter: E September Letter: P
February Letter: B June Letter: H October Letter: R
March Letter: C July Letter: K November Letter: S
April Letter: D August Letter: M December Letter: T
Ratio Code Chart

Letter: A M20 Ratio
Letter: B M21 Ratio
Letter: C M22 Ratio


Jeff G.

You have a 1966 M20 assembled on May 31st, 1966 and installed in a Full Size passenger car or a Chevelle built at the Atlant, GA plant.

$275.00 is a very good price if it's been rebuilt by a reputable company.

Ed

I bought it tonight, since tomorrow is pay day. It had rebuilt last year that was reputable mechanic here in town that I know and the guy never paid him for the work. Took off the the side cover and the look great. I guess it never hurts to ask. Thanks for the information!!