This one (above) is the one you saw on Dauntless Motors' web site under "off road rigs." Jay put it together for us. Cost about $4K with paint, mounts, and a special wheel/brake configuration; other than that it's a fairly basic setup. If we decide to stay with this for a while, which looks like we will, it will be going back for a front end mod (about another $2K) using a leading link. But it will handle much better and not pull to the right so much. (That's just what hacks do.)
This is a Sputnik, imported from Russia. Dauntless imported them for about 5 years, but they aren't being mf'd any more. There are plenty lying around dormant here in the states, you just have to look around. The Sputnik is an excellent match for the 650. The only thing lighter is a Velorex, but they are fiberglass and maybe too light. This one comes up enough as it is!
Hacks are definitely weird to get used to. They are not like a bike, they don't lean. But they are a blast, and this allows us to get out and ride and travel with our two-year-old daughter. We've already put 3K on it this summer with the kid and she loves it. Also doing a lot of dual sporting with it. This rig handles great in the dirt. Keep in mind we're hauling a little kid and her camping gear; if you were going to haul an adult you might want to go to a slightly smaller countersprocket. But it seems to have enough power for us. I can cruise about 65mph like I always did and still climb hils while maintaining 55mph. I got 50 mpg when I checked, and fuel range is around 180-200 miles on the stock tank.