MTD made a few differnt bikes, the smaller bikes used a brake band over the wheel hub, larger bikes were usually spoke wheeled and from what I have seen were standard internal drum brakes on the hub like a conventional motorcycle
the only example I have is from a bike I rebuilt a few years ago, it was the smallest framed bike they made so I dunno if it will help or at least give you an idea of what they did.
There was a special mount plate that held the brake cable and pivot pin for the band to ride on , the hub was the drum. I want to say that the other 6" wheel bikes they made with all the odd bends in the frame was the same way, only on the left side of the bike, due it it having a jackshaft type driveline.