The SM420 is a much much more robust transmission than the 3 speed. That's why I switched. Plus, if you want a floor shifter, there is no easier way to get one . Plus you get the creeper gear. Plus it's still a stock configuration. 2nd through 4th is functionally the same as 1st through 3rd of the 3 speed. Final drive is 1:1 same as the 3 speed.
I think the SM420 plus Patrick's lower ratio differential gears would be about perfect for a daily driver. Forget all this swap the rear end, overdrive tranny stuff LOL.
Kurt
