M30 Transmission

The M30 transmission is a variation of the venerable 4L60E transmission, and is manufactured by General Motors.  It has four forward gears, the third of which is a 30% overdrive.  M30 itself is a RPO code.  It stands for:


There is a different RPO code for every GM transmission, sometimes several.  Here’s more on GM Transmission RPO codes.

M30 Specs

The M30 transmission has an aluminum case and weighs 162 pounds with all the fluid in it.  It has been made available in a wide variety of GM automobiles, from the Corvette all the way to the Silverado.   There is sometimes an M30 stamp on the case, similar to the MD8 stamped on the 700R4.

1’st 3.06

2’nd 1.63

3’rd 1.00

4’th .70


You’ll find the 4L60E production code on the passenger side of the transmission by the pan toward the rear.  It is a much more accurate way to identify any transmission.  Even if you do happen to have M30 transmission, that is still very vague.  What you need is to properly identify the 4L60E.

M30 Transmission
Every modern GM vehicle has one of these sheets in its glove compartment. Use it to verify the vehicle has a M30 4L60E

The easiest way to identify the M30 transmission is to look at the glove compartment tag.  Each GM vehicle comes with one of these tags.  It has all of the major RPO codes listed on it.  These codes tell you everything from the paint that came on the vehicle, to the engine, and even the transmission.  For instance, the LM7 engine is the 5.3L LS truck motor and the LR4 is the 4.8.  You can’t tell them apart by looking at them, but the RPO code on the build sheet will tell you exactly what you are looking at.

The M30 transmission is compatible with any other 4L60E of the same year, but it is worth noting that GM changed a lot as far as how the clutches handled friction in the torque converter, what the torque converter was even made of, bellhousing bolt patterns, and more.

8 thoughts on “M30 Transmission”

    • Carl, no they can not be swapped for one another- at least not in a practical sense. M30 needs an ECM to control its shifts properly. There are expensive controllers to facilitate this, but they are extremely cost prohibitive.

  1. I just bought a rebuilt 4L60E tranny for my 2000 Silverado 4×4 and the tranny I pulled out had a great big M30 on the side along with the 4L60E ,now the guy wants my old tranny for the core but is the M30 a better tranny,should I keep it and have it rebuilt,the tranny I just bought was built heavy duty,at least
    that is what I paid for

    • Josh, You’ll definitely need one with the one piece case. The later ones use a two piece bellhousing that hooks up to the Gen IV truck engines.

      • So pretty much any one peice will be fine? I read somewhere I’d only be able to put a 93-94 one in but a lot people said any single cases would do

        • 93 should be a 700R4, 94 ought to be a 4L60E. 94 is by itself, (as well as 95 too) as a 1 year only transmission because of internal wiring and valve body.

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