I still haven't completed this yet, but we kept the sm420 and we bought a few used parts to do this, but we don't seem to get to it. Come out of the back of the sm420 with a shorty transfer case drive shaft. Go into the overdrive part off an old overdrive transmission. It needs a 6 spline yoke like on tractor stuff to do it. Fleet Farm has some of the stuff. The overdrive tranny half needs a plate on the front to keep the lube in and the plate needs to have a bearing hole in it. That's the plan, but as I said, we haven't done it yet. We have the parts, but the short drive shaft between the sm420 and the od tranny half needs to do a yoke switch because they are designed so that people can't just hook up cars stuff to tractor stuff. I don't know why tho. - Scott
