1968 T100S Wiring Harness Question

[John Guntner]

I am installing a new wire harness in the bike, but I do not understand which light bulb would be used in that socket.
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[otis71]

The British used Lucas bulbs that are different than the ones Americans are used to. From what I can see without knowing more it looks like triumph part #281. Any British parts vendor should be able to confirm number and have them in stock.