I actually picked this up like 4 years ago in Wisconsin. The owner had it apart but everything seemed ok, so I put it back together. I couldn't get the original Sachs 277 cc two stroke motor to run consistently so I picked up a Honda GX390, 13 hp 4 stroke slightly used on ebay and a new Comet clutch. Its been like 4 years in the making but I've finally got it pretty well figured out with a few new chains and sprockets (there's a lot of them)
This thing's around a 1970...it's an amphibious ATV though I also think of it as being an American ATV...back then the Japanese were the ones that brought us good dirt bikes, 3, and 4 wheelers...we had boats with wheels. It's made of Borg Warner "Cycolac", aka ABS. The drivetrain and axles are on a steel frame inside the tub so the plastic isn't really exposed to forces. You've got two sticks and a throttle, with the sticks controlling a small transmission with brakes and clutches inside and a centrifugal clutch on the motor (CVT, like a snowmobile, go kart, etc) The Firestone tires have a max rating of 2 PSI...you can push them in pretty far with your foot.
And it will go anywhere. I'm working on the video footage but I've driven over fallen logs, steep ditches...its pretty sweet obviously with 6 wheel drive, crazy approach and departure angles, and a really low center of gravity. It's really slow in the water just using wheel power (like 2 mph at full blast). I need to work on it some more but I've added an outboard motor mount so I can at least use a trolling motor. It isn't too heavy...I can pick up one side of it so its not bad to trailer with my Forester.
It's pretty sweet having traction and torque...I was able to pull in the fishing boat in a great show of power lol. It's fast enough though...I can pull the leaf and clippings sweeper around the yard a lot faster than the mowing tractor can. It's crazy fun.
It's like unstoppable as long as your have the courage to shove the sticks forward. A lot of these old 6x6's didn't have reverse but this one does so you can get out of nasty spots. The Amphicat was one of the better ones and they're somewhat common as far as these go. A lot of these things were cheaply engineered (and thus they're not around anymore). All the chains and sprockets eventually do wear out and are tedious to replace. The ABS isn't that think and can be broken if you hit something. They often had hollow axles which are a common thing to have to fix on old 6x6's but the Amphicat's got forged axles. I have brand new seals for it which I'm going to put in soon to stop the slow seeping. It's said that they're "impossible" to sink due to the air in the tires, but nevertheless I wear a life jacket when crossing the lake (30-some acres)
Argo and Recreatives Industries still make 6x6's (and 8x8's).
Haven't tried them but I've also got an original set of snow tracks for it.
The pix and upcoming footage are from our cottage on Eagle Lake in Mancelona, MI, shot by my bro, with his Canon D30 (I think)
I didn't hit the water very fast...it'll make a lovely splash at full blast but won't really get you wet