Does anyone know what the gasket that is between a piece of flex pipe that is affixed to the exhust manifold up top is called. It is affixed with two readily seen clamps.

It sounds like you're talking about the assembly that runs to the EGR valve - a corugated pipe $92 plus $28 for ring clamps. I do not believe there are any gaskets involved. Am searching junkyards for the pipe assembly myself to fix an exhaust leak on the 240D.