I see no logical reason as to why you can't use the "3-bolt" bell-housing on a 500D. But yes, you WOULD have to give the starter more support. (A) you MIGHT be able to weld on a little stiffening plate on the ENGINE side of the top bolt-hole PLUS, (B) you also fit a "Starter support bracket". These are available from "Passione" (in Italy---got any relatives or friends over there?)---part number:---ELE22C---cost E45