You might try grinding the pin flush with the knuckle on both sides to nice, shiny metal, and then heating the knuckle and whanging on the pin with a pin or drive punch instead of a drift. I don't think the pin is hardened, though it might be, but you might have to resort to drilling, or at least trying to drill it. If you can drill it, I would only drill about three quarters of the way through it, and get into it with a pin punch, heating the knuckle, of course.