Triumph Repair: Parking/signal light bulb, auto parts store, double contact

Question
QUESTION: Howard. This would seem to be not a big problem but it is if I'm guessing. My front parking light/singal light bulb burned out on my 1974 Spitfire. Well I was trying to find the bulb number I need to replace it(don't see it on old bulb).Looked in my manual. It gives some old Lucas #, no help there. Mine has the single bulb that is the parking light and turn signal light.Looked everywhere on to no avail. Your my last hope. I don't want to replace it with wrong bulb since Lucas systems are so quirky. Thanks Jim

ANSWER: Hi Jim,
I doubt you are planning to mail order the tinny bulb so I would suggest a simple solution. Just take the old bulb to any auto parts store and match it up. That's what I do.  I don't have a cross reference for bulb numbers.
Howard

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QUESTION: Howard. I orginnaly took it to AutoZone,before I sent this question..  Person gave me wrong bulb right of the bat.Mine had two contacts on bottom one she said I needed had one. Lost confidencce in them.  I guess my question is: As long as its a double contact bulb that says it's for turn signal/parking light is ok. There seems to be a lot of those exact kind with differnt numbers. If they were all the same wouldn't they use universal number. Guess I'm overanalizing this. Whew! That's what British cars will do to ya.  Jim

Answer
Jim, You need to go to an auto parts store in your area that mechanics go to. Many of those "grocery store" type stores have no clue what an auto part is. Take the bulb and compare the locations of the small pins on the side of the bulb and the location of the two contacts. Anyone who tells you a single contact bulb will replace a two contact bulb has never seen a bulb before.
Howard