... it's shown on the Tbird Electrical Assembly Manual. ...
The diameter of the hole and distance to the left the headlight switch is shown on page 25 for '55
and page 65 for '56. (those measurements are the same both years)
I'll assume you have the '55/'57 T-bird Electrical Assembly Manual. But if it's like mine it doesn't show the bezel or lens outer diameter measurement you're looking for.
The reprint '55/'57 Thunderbird Assembly Manual I have lists the part numbers for those two years of warning lights (yours may as well).
But it isn't the same as the part number on the box in your photo, which looks like FDH-15848-A
From the T-Bird Elect Assembly Manual . . .
'55) Parking brake signal lamp kit, FEA-15848-B
Lamp assembly FDH-15850-B
'56) Parking brake signal lamp kit, FEF-15848-A
Lamp assembly FDR-15850-A
Also, if the illustrations on those two pages are to be believed, the lens for the '55 warning light has the word 'Brake' on it and the '56 does not.
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