5590 x1. The rare to find now, XK140 & XK150 plastic "J" Light Double Contact Bayonet adapter that fits into the large 2 1/4" hole in the rear of ORIGINAL LUCAS J headlights (not Repro). Lucas will be cast into the glass of originals. (recently rebuilt J lights may have XK120 style backs with 1" holes. In this case SEE : 5391)

These will be originals and are often missing the insulator board, but we will add a pair of springs and copper rivets to solder to the wires as bulb contacts. You will have to make up the twin hole insulator for them if we cannot provide one. Original  Ref 5298. Lucas 554855