Just picked up this 1978, 4sp, radio delete, 305 2bbl

[Jdigitty88]

I found mine behind the hood liner.

 

[oldsmobile joe]

it might be a factory 4 speed, but its not a muncie trans. it should be a saginaw 4speed. there is no info in the vin or the body tag that is located on the drivers side of the cowl. but if your car still has the emission sticker on the fan shroud, there may be info there that we can use. on the emission label, it will state the engine size in the left upper corner. this should match your engine. now also on the label with be the ign timing and idle speed specs and the discription of how to set them, if it says to place it in drive, (D or DR), then the car was originally an auto. manual trans car will have specs that state N for neutral.
joe

 

[aj1434]

Welcome aboard AJ.
Looks like you found a nice '78 Malibu wagon. You'll have to post some more pics of the car.
It looks like an interesting find.
First check under the rear seat for the build sheet. They've placed them in various locations in these cars. If I recall correctly, mine was over the headliner board. They've been found above the gas tank, behind a door panel, etc. I wouldn't expect you to start ripping the car apart in search of the build sheet. It might have been found by the previous owner.

Just added a few pics

 

[aj1434]

it might be a factory 4 speed, but its not a muncie trans. it should be a saginaw 4speed. there is no info in the vin or the body tag that is located on the drivers side of the cowl. but if your car still has the emission sticker on the fan shroud, there may be info there that we can use. on the emission label, it will state the engine size in the left upper corner. this should match your engine. now also on the label with be the ign timing and idle speed specs and the discription of how to set them, if it says to place it in drive, (D or DR), then the car was originally an auto. manual trans car will have specs that state N for neutral.
joe

Thanks, I will look for that info tomorrow. What is M-20 stand for then?

 

[Ribbedroof]

It just hasn't been discovered yet. It's hiding somewhere in the car.

Not necessarily, Jack. Per a discussion with GM in about 1985, the build sheet was supposed to be discarded when the component it was attached to was installed. Obviously, this often didn't happen.

Build Sheet is the only way to figure It out I guess huh.

You could check for the partial VIN on the trans case. I don't know that being "factory" really is that big a deal, especially if it's going to be modified, but it is a cool bragging right, I guess.

Fun car, either way.

 

[Ribbedroof]

Thanks, I will look for that info tomorrow. What is M-20 stand for then?

4 speed manual transmission... it's an RPO code, not a specific component identifier.

It's actually MM4 for a G body era car after the 1978 model year, it was still spec'd as M20 for 1978

 

[oldsmobile joe]

i'll have to look it up. in the late 60's and early 70's m-20 denoted muncie 4speed wide ratio. they may still use the code, but changed the trans to a saginaw. the muncie trans production stopped in 73 or 74. its possible the PO swapped out the saginaw for a muncie.
joe

 

[oldsmobile joe]

4 speed manual transmission... it's an RPO code, not a specific component identifier.

yes and no, it is an rpo code, which gm used to specify a particular component based on the car and year. for example, an lt1 eng in 71 is not the same as in 93 or in 2018.

It's actually MM4 for a G body era car

that may be correct for a g body. but his is an A body. in my 79 service manual, the 4speed manual is listed as the m-20 option.
joe

 

[oldsmobile joe]

wow, sorry ribbedroof, my computer is acting up, I'm just now seeing your full response as well as aj's pics.
joe

 

[CaliWagon83]

This wagon is beyond cool. Factory V-8, manual trans...awesome. 😎