All of the "old style" DBs I've seen have had the disc brake. Oddly, some "new style" DBs had a drum, some had the disc. I don't think there's much information available concerning model year differences; cheap Chinese minibike, no one cared. I like the old style DBs; the only thing I don't like about them is the inboard rear axle location, I'd relocate it outboard, increasing the wheelbase, making it less wheelie prone and more stable.