With a quantity of two pieces, the Washer,10.5x26x2.3 is the most used part in the FUEL TANK diagram.
Some items from this specific schematic: Ring-o,fuel Tap,1.9x1, Tank Comp Fuel,p.whit, Tap-assy,fuel, Packing,fuel Tap (nas).
thirteen components are shown in this Ar50c6 1988 Europe Uk Gr Fuel Tank exploded diagram.