couple of things, first, the loader is supposed to fit the 5205, and 5305, but not the 5105. That doesn't entirely make sense to me as far as physically fitting the machine.
Second, my information comes from a bushhog dealer who had trouble getting in touch with bush hog, as if they didn't really want to devote engineer time to him and his question. I also felt like they gave it a cursory look without analysis on the adaptability of the loader to the machine.
so to answer your question, the people that made this machine are in the business of selling new ones. why tell me the old one will fit, make me buy a new one!
To turn the question around, why would you completely trust everything a merchant tells you? Their keenely interested in selling me a NEW unit, not that old one that is already paid for by thye dealer. Besides, I live in the poor man's world world of making things fit and this sounds fairly close.