Try this link. They are next door to you. I have a D190Z. I emailed them and they have a Valve Grind Set (gaskets) at a quite reasonable price. I was actually surprised they had what I wanted. I don't know about your D12 but Mercruiser bought BMW Marine in the late 80's and continued to produce my engine (different name) for years. Also get in touch with Rich Langtry, BMW Marine/V 12 Engineering in Canada. He gets parts from Navalis Marine in Germany. I have ordered from him/them.