Exhaust Gasket

[The Hatter]

I need an exhaust gasket for an 86 350i, the one between the middle section and the rear section; roughly under the fuel tank. I'm not too happy using silicon, I'd rather have the correct part. It's 2 1/2" bore with 3 holes; I guess it's a part off a SD1 rover or Range Rover or something similar... anyone know what it's off?