Lock nut, carburettor adaptor, screw on, Norton singles, alloy

Lock nut for carburettor adaptor / manifold, that screws into head for spigot mount carb, Thread 1-3/8 inch 26tpi, AF1.665 inch, 42mm Thickness 0.2 in 5mm, thin hard aluminium alloy, flat one side chamfered the other, each
Original part number
9132; A3/154 - Carburetter (sic) Adaptor [not listed in parts books]