I'm considering swapping a 4 speed in my 68 cutlass ragtop and looking for opinions. The car has a mild 455 (400hp) and 3.08 rear end, I'm planning on changing the rear end with a 3.31 posi. I'm looking for a wide ratio 4 speed. Should I look for a M-20 or a ST-10?? What are the advantages? Thanks.

 

There is also the AutoGear 4-spd option. ie. M22W, M22Z, M20

 

I'm not farmiliar with the auto gear option? Can you give some details?

 

Basically a clone of the original Muncie. All new parts though, new stronger case, stronger mid plate, new gears (Italian are the ones to get IIRC). M22W has similar gearing to the original Muncie M20. M22Z has like a 2.98 1st gear. Pic below.

 

Thats a nice peice, I'd like to do this on a budget though so I'm probably stuck with a M-20 or a ST-10

 

I would install the m-20, and with the m-20 you can use a nice original shifter. The m-20 may be a little cheaper.

 

I've noticed an original 442 shifter and linkage on ebay can bring $500-$600 nice peice but not cheap.

 

Use a replacement shifter from hurst

 

One more, its best not to cut corners on a 4 speed conversion. Example, if your crank is not drilled for the pilot bearing, then, the motor would need to come out. Also, what year is your block? After 1974 or so, they stopped producing the block that has the mounting point for the clutch ball.

 

thanks for the info. My crank was drilled for a 4 speed from the factory, I'll have to have a look at my block though for the mounting point. If its not there I'm guessing you could go with a hydraulic clutch?

 

I remember seeing on here or ROP, a member made an adapter that bolted to the block and was able to put the ball stud on the adapter.