| Also known as | 3966, 987R |
| Diagram | Fig. 18 — HEADLAMP, SPEEDOMETER, TACHOMETER · ref 27 |
| Subsystem | electrical |
| Listed in parts books | 1964–1968, 1971, 1974 |
Bulb, 3.W. M.E.S.
A 3-watt screw-base (M.E.S.) instrument bulb used behind speedometer, tachometer, and tail lamp faces.
This is the small screw-base bulb Lucas fitted behind the speedometer and tachometer faces, and it also turns up in tail lamp figures in our books. It's a 3-watt bulb with an M.E.S. (miniature Edison screw) base, so it threads into the bulb holder rather than bayonetting in — check the socket before you order to make sure you've got the screw-type holder and not a bayonet one.
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Our catalog shows this part across a long run of years and a good number of appearances, which tells you it's a commonly needed item rather than something tied to one specific model or figure. It's listed as superseded by 987R, so if your parts book or an old order shows that number, it's the same bulb under Lucas's later designation. You'll also see it cross-referenced as 3966 in some records.
This is one of those bulbs worth having a spare of in a drawer — they're small, they burn out without warning, and a dead speedo or tach light is an easy thing to fix once you know which bulb you need.
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