Well.... there are several of them hiding out at the G-Team shop. That's the G-Man's preferred tranny, simply because they are bulletproof. About impossible to find, but about impossible to blow up too. He typically reconfigures them to a 2 speed as a rule. You have to watch them as the 350 Peerless is more or less identical in appearance, but it runs bushings instead of needle bearings like the one above. They can be refitted but it's a LOT of work! And, the G-Man says they don't stand up with the bushings.
Identifying features on the two models, would be the closed end caps on the shafts on the 400 model. The 350 with bushings the ends are open, clearly evident there is bushing and shaft there.
More pictures in the thread here --> http://www.heymow.com/viewtopic.php?t=514&start=0
And, I am told... haven't seen it myself, but Squidd would know... that many of the Peerless 350/400 and Peerless 600 parts are interchangeable. They are essentially the same tranny, the 350/400 is a stand alone chain drive unit, the 600 is a transaxle. If you look back at the 600 pictures Squidd posted in this thread, on the front view it's pretty evident.