8D is a mirror image of 4D, so the bolt at the top points outboard if you fit it to a D2, rather than inboard which it should do.
However, Mike and I managed to dismantle an 8D and get both the balljoints and the polyurethane sockets out of it, and then refitted them to the 4D plastic arm which then fitted back on a D2. Most of the time I just make a new arm from M6 rod ends, but we had the bits on the bench so gave it a go and it worked