This is the plastic mount for the fuel pump assembly inside the fuel tank; this is to fit the pre 01/1993 52mm diameter pump. This part has five mount holes, and a flat edge (see TAA64629 for a detailed photo).

Please note: there is a version of this item fitted to bikes produced before 05/1985 that had six mount holes instead of five; this item replaces that earlier one, in conjunction with the fuel op FUK64629.