On Thu, 15 Oct 2020 10:19:01 +0100, "Dave Plowman (News)"
wrote:

In article ,
Thomas Prufer wrote:
And BAY15d may have different-height pins, with two base contacts and case for
ground, for double-filament automotive lights that need a single mounting
orientation (brake & running light, I think is one...)

There are offset pins (height wise) for the older stop/tail bulb. And then
a different offset (not 180 spaced) came in for others - like amber
flasher bulbs.

There also seems to be 1156 and 1157 that is supposed to refer to the
pin orientation but getting all that to line up Bay15D 1156 (
supposedly non offset pins) and a single filament wired across both
terminals and not terminal to base *and* with the LEDS facing all ways
and at a reasonable wattage / light output, seems quite an ask. ;-)

I may have found such on ebay and I've asked for confirmation of fit
in general, wiring and wattage.

It sorta suggests it's polarized and if it is I can stick a blocking
diode in there or bridge (single diode less lossy), in case I or
someone connects it up backwards.

Cheers, T i m