The SM420 isn't going to get you going any faster than your current tranny. The 4th gear in it is a granny or stump puller LOW gear. It's the type of tranny that's generally used as a 3-speed unless you need a lower gear to start a big load moving. Both it and your 46 3-speed have a 1:1 high gear ratio.
You are probably wanting an overdrive tranny - T5 or similar. Those will require you to go to an open driveline to the rear axle.
Hmmm, you mean 1st gear is the stump puller gear not the 4th right?
Anyway this does help. I wondered what the ratio might be. I won’t do a T5 due to all that is involved. I wish it were easier. What I did find is a ring and pinion set on the filling station.com web site for about $400 so that’s likely what I will do. The SM420 was offered to me and so I wanted to look into it.
Thank you.
Bob
