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!