PY Online Forums - Bringing the Pontiac Hobby Together

PY Online Forums - Bringing the Pontiac Hobby Together (
-   70-72 GTO Tempest & LeMans TECH (
-   -   Muncie '330' RPO M13 parts list (

unruhjonny 10-25-2019 04:18 PM

Muncie '330' RPO M13 parts list
1 Attachment(s)
I am posting this here in an effort to help anyone in this community who has a 1969-1976(?) Muncie '330' (RPO: MC1,M13 ect) three speed in their car, because it has seemed to me as though getting any good use able information on these three speeds is very tough.

I have chosen to post in this subforum rather than the 70-73 Firebird subforum where I am usually hanging out because it seems as though infinitely more 1970-1972 Pontiac A-bodies were built with this transmission than Firebirds.

I recently acquired a October 1975 pressing of the Borg Warner "Standard transmission gears" catalogue - apparently this is code for "passenger car; manual transmission parts".

I first came across this particular catalogue at an old transmission shop in Oregon, and had been searching for a copy of my own since... thankfully I found one in less than a year!

Here's a jpg version of my compiled information:

Well that didn't upload as I had hoped, so here is my typed version of the list so that anyone reading this can be copy what they need:

Muncie “330” three speed complete parts list
format = ‘part type’ : ‘description’; ‘GM part number’/’Borg Warner (SR) part number’

Countershaft cluster gear (car): R27-22-17-16T; 3911950 / AWT306-8A
*Countershaft cluster gear (truck/full sized): R29-23-17-16T; 3911985 / AWT306-8
Countershaft: 1-1/2”x11”; 3911954 / WT306-3
Mainshaft: 21-1/8”OA S42-42-27 Spl; 3911960 / WT306-2
Mainshaft Reverse gear: BH S36-L30T; 3911964 / AWT306-36
Mainshaft first gear: GH S36-L32T; 3911961 / WT306-12
Mainshaft 1st synchro stop ring: Bronze S36T; 3911974 / WT306-83
Mainshaft 1st & reverse synchro assembly w/rings: <nothing noted>; 3911968+ / AWT-306-80
Mainshaft second gear (car): S36-L27T; 3911962 / WT306-11A
*Mainshaft second gear (truck/fullsized): S26T-L35T; 3911988 / WT306-11
Mainshaft 2nd & 3rd synchro stop ring: Bronze S36T; 3911974 / WT306-83
Mainshaft 2nd & 3rd synchro assembly w/rings: <nothing noted>; 3911968+ / AWT306-2 1/2
Main drive gear (car): S36-R21T; 3932210 / AWT306-16
*Main drive gear (truck/fullsized): S36-R18T*; 3932211 / AWT306-16A (*=not noted, my notes)
Reverse idler gear: L21T; 3911956 / AWT306-10
Reverse idler shaft: 2-7/8” OA; 3911959 / WT306-35
Small parts kit: --- / SP306-50

I have come to understand some of the small parts are shared with some four speeds, but I haven't yet deciphered this - it does look by the description as though the synchro rings are shared with the Muncie four speed, and maybe even the BW-T10, but I am seeing three different part numbers right now.
If anyone can add to this what parts interchange (eg: roller bearings) I'd appreciate you chiming in.

I had previously thought that the only two differences between the truck ("A" code) and passenger car ("B" code) transmission gear sets were the countershaft cluster gears and the main drive gear, but this catalogue has shown me that the mainshaft second gear is also different;
add to this the fact that most trucks and full sized cars which used this transmission were column shifted, so they used a different tail housing, AND the front bearing retainer was a different piece between the car and truck, and there is some variations to be noted.

Here is some additional information I have compiled:

Main case casting number(s): 3911982, 3952662, 3987948, 6273282(?; 1974 1 ton case)

Side cover casting number(s): 3911847, 3952646

Tail housing casting number(s): 3911942 (c/w shifter mount), 3911984 (column shift)

Front bearing retainer casting number(s): 3911977 (car), 3925835(?; truck)

I hope this helps someone!

Mister Pontiac 10-26-2019 04:15 PM

Thanks Johnny. This will be helpful when I go thru my spare M13 next year in prep for install in the 71 GTO. :)

tallyhoe 10-27-2019 12:42 PM

Thank you very much! Anything about my trans is much appreciated!

SD455DJ 10-28-2019 12:41 PM

Thanks for doing that Jonny. All of us M13 owners appreciate your hard work.


unruhjonny 01-14-2022 01:53 PM

1 Attachment(s)
I just hit personal paydirt!!

My almost OCD level of three speed parts scrounging has paid off!
I just confirmed via a master parts manual, spurred by discussion on NastyZ28 that the reverse lock out rod used on Saginaw 3 & 4 speed cars, is the exact same rod used on Muncie three speed cars!
Group 4.035 "ROD, STEERING COLUMN LOCK" (lower, not upper rod).

I know this is specific to Firebirds, but I figure it's worth mentioning here incase someone in the future can use this information.

I bought an ITM 3 speed shifter & reverse lock out rod some time ago from a membber here, and filed the parts away;
It appears as though unlike the Muncie reverse rods which had stamped (abbreviated) part numbers, the saginaw rods do NOT have a part number.
I'm attaching an image of a members former(?) car with the rod shown so that the shape is clearly seen.
This is NOT the rod used for Muncie four speed, or Borg Warner four speed cars (both of which ARE different).

Also, you need to confirm that you have the correct bell crank, and reverse lever on the transmission.

hawkins69 01-31-2022 12:56 AM

Thatís great. Iím looking for info and parts for 1971 m13 3-speed GT-37 project.

unruhjonny 02-10-2022 01:38 PM

I'm going to give this a bump, because I realized that I neglected to mention two other things;

1) As I have understood it, the 'B' gear set transmissions were always set up for a floor shifter (which would explain why the 70-71 Firebird ordering shows it as a "floor shift only");

The tail housings are cast with and without provisions for a floor shifter, so odds are if you found a donor truck transmission, it will not have provisions to mount a shifter.

2) the trucks used a larger OD front bearing retainer, so cars need the smaller one - unless you plan on using a truck bellhousing.

Casting numbers are sometimes REALLY hard to read on these castings, so I am giving multiple numbers, incase one or more of them is incorrect:

Tail housing w/column shift: 3968038 / 3911984
Tail housing w/floor shift: 3911942

Truck front bearing retainer: 3825635
Car front bearing retainer: 3911837 / 3911872 / 3911976*

* = this is a part number taken from a GM parts catalogue.

unruhjonny 05-10-2022 11:14 AM

1 Attachment(s)
Incase anyone is interested a Muncie 330 "B" (car) main cluster gear recently showed up on eBay;
This is one of the few parts which is specific to the "B" gear set.

I already have a spare one of these.

eBay link
(main image attached here so that seeing it is not dependant on the ebay listing)

All times are GMT -4. The time now is 07:29 PM.