Turbo 350 to Muncie M20


New member
Hello everyone I am very new to working on old Pontiac’s and I am looking for the easiest way to swap my turbo 350 automatic trans with a Muncie m20. From the little research I did it seems fairly simple considering the drive shaft is the same for both transmissions. Will I run into any problems and what’s the easiest way to find parts?


  • D73D5E9F-8919-4E4E-81FC-62CFD9313E22.jpeg
    483.4 KB · Views: 1


Active member
Belleville MI
You will need alot of small parts that are not that easy to find, the Bellhousing, flywheel, and clutch fork & return spring should not be an issue, but parts like the clutch & brake pedal assembly, the clutch Z-Bar, the frame bracket for the Z-Bar, the Z-Bar ball stud that mounts to the engine block, and the 2 push rods to activate the clutch could be tricky. To do it right you will also need the shifter, shifter porch for the transmission tunnel, back drive linkage for the reverse lamp switch, and a Switch that is activated by the clutch pedal so the starter will not engage unless the clutch pedal is fuly depressed.

I have done a few conversions on 66 & 67 Leman's and it takes some work. on your later car the frame bracket bolts to the frame so no welding is needed like the 67 and earlier cars, also the shifter porch can be screwed down (as was done at the factory on 68 and later cars) Alot of the parts are reproduced for GTO's but not all of them, and the last time I checked the repo Z-bars were not complete, as they lacked internal bushings to mound them.

The easiest way is to find a manual transmission parts car, even a 3-speed column shift car would get you along way there as long as it is a V8 car and not a 6 cylinder car. Just be aware if you have to buy the repo parts they are not cheap, and you are correct the driveshaft anf the yoke should be the same between a T350 and a 4-speed Muncie, as long as the Muncie you find is a 1972 or older, starting in 1973 the 4-speed Muncie's started using the larger output shafts and yokes used with the T400 automatics.

I am not sure if you will need to modify the trans cross member or maybe just need to reposition it to a different set of holes on the frame.