Can you post a picture of it. I've never seen a S67. I had a muskeg carrier with a 4.236 Perkins diesel with a 5 spd new process transmission that I sold to a little snowmobile club. Well I still own 1/10. They don't travel very fast, probably around 13 mph if I remember, so you just select the gear for the speed/power you want to travel. There is not much shifting involved to change to an automatic transmission, but there is lots of room if you do decide to go ahead. A tranny cooler can be mounted in front of the radiator, and your drive shaft will need to get modified and shortened. Then it's just your shifting linkage to get worked out.
