4 speed Manual Trans info?

[Boghog]

I have a 84 GMC High Sierra 1/2 ton shortbed 4x4 350 ,4 spd manual trans ,208-c transfer case, 3.73 axle's....what I'm looking for is info on GM truck 4 spd trans.......my trans has a long shift ratio between 2nd and 3rd and I don't remember the shift in my 78 chev pickup being so long between 2nd and 3rd....what I mean is in 2nd you have to get the rpm's up and when you hit 3rd it just drops the rpm's fast....that what i mean " LONG" between 2nd and 3rd......so my question is are there any websites for this info and can you look at a trans tag and tell what the gear ratio's are before you put one in your rig?...I can't find one on my 84 and the build sheet code is MM4-4speed manual so what trans is this?....

thanks

Rob

[Captkaos]

If it is factory it is the same SM465 used in all 1973-1987 (1991) C/K (V) pickups and Blazers.
The ratios are: 1st: 6.55 2nd: 3.58  3rd: 1.57  4th: 1.00 

[VileZambonie]

Isuzu M-150 (77.5 mm) 4-Speed
Muncie CH & SM-465 4 Speed
Muncie 3 Speed
MUNCIE 4 (117MM) Speed
MUNCIE 5LM60 (HM-290) 4 & 5 Speed
Saginaw (76 mm) 4 Speed
Saginaw 3 Speed
Tremec 3 Speed
Warner T-4C 4 Speed
Warner T5 (77mm) 5-Speed
Warner 83 mm 4 Speed
   
All available GM manual trans for your truck.... ID which one you have in there for sure.

[zieg85]

MM4 : MERCHANDISED TRANS, MAN 4 SPD PROVISIONS

I did a search and found the above statement on that RPO trans code.  I saw another application on a 4 speed mentioning overdrive.  I have several MY6 4 speed overdrive but it is more a car trans but put in 81-87 GM trucks.  Is this a 4 speed with a granny first gear?.  Interesting... either way.  If it doesn't have the granny it could be an overdrive which somebody didn't hook up the linkage right.  They might have not installed the shift lever the right way which 3rd position may be overdrive and 4th is direct drive.  I know my 3rd/4th lever is reversed that way on my New Process MY6

[Boghog]

MM4 : MERCHANDISED TRANS, MAN 4 SPD PROVISIONS

I did a search and found the above statement on that RPO trans code.  I saw another application on a 4 speed mentioning overdrive.  I have several MY6 4 speed overdrive but it is more a car trans but put in 81-87 GM trucks.  Is this a 4 speed with a granny first gear?.  Interesting... either way.  If it doesn't have the granny it could be an overdrive which somebody didn't hook up the linkage right.  They might have not installed the shift lever the right way which 3rd position may be overdrive and 4th is direct drive.  I know my 3rd/4th lever is reversed that way on my New Process MY6

Yes mine has the granny 1rst gear and its a top loader.....to me it looks like any 4 spd out of any 73 - 87 but I'm not sure what year they started to change these trany's to the later model?.....the more I think I know my 73 - 87's the more I don't know which is the beauty of being head over heels for these trucks!......

[zieg85]

You should have the same trans as I do in my 85 then.  Just love it.  Can be in 4th around 30 mph with no problems with the rpm drops on mine, even pulling a loaded trailer.  I know there was a terrible drop with the F!@d 4 speed OD between 2nd and 3rd in a 86 Bronco Full size I had once but never experienced a problem in the gear ratio's of my GM's

[Captkaos]

The only transmissions I have seen in the K series are the 83MM (3 speed with overdrive) generally only on diesels as they are weak, Muncie/Saginaw 3 speeds, or SM465 which is what is in 99% of them here that have manuals.  They didn't change the transmission for the SM465 on this bodystyle, it did get and update, but still the same trans.