What type of bulbs are needed for fendertop indicators?

TTBOMK #168 was never used in any fendertop turn indicators, though it was used in '72-up sidemarker lights (on the sides of the fenders). Different lamp. UPDATE: Wrong, see below, 168 was used in some fendertop indicators.

Pick up a ten-pack of the premium version of the correct fendertop signal bulb (with nickel-plated base that won't corrode) from my former employer here, or spend just about equal money on two lower-quality bulbs elsewhere.

(…and while you're at it, make your '68-'71 sidemarkers 60% brighter with these, your '72-up sidemarkers 60% brighter with these, and your reversing lights nearly 100% brighter with these.)