Depending on the model, these various seals are located inside the vacuum pump and between the vacuum pump and the engine block.
Tandem Fuel Vacuum Pump Seal Repair Gasket Replacement for Car
BMW M47 M57 Vacuum pump seal repair kit - High-quality seals and gaskets
Vacuum pump seal repair kit A6462300165 / 6462300165 for Mercedes
Vacuum pump seal repair kit 94811005006 for Porsche
Vacuum pump seal repair kit A64623065 / 64623065 for Mercedes
Vacuum pump seal repair kit 9A111009002 for Porsche
