Found some 921 Creek-based LEDs on EBay. Similar to these, but from another seller:
http://www.ebay.com/...b-/280993575923
Seem to be pretty bright, don't have a fair comparison with 921 incandescents, because those bulbs already had a lot of miles on them.
The base did not sink in as deep as I would have liked, since the socket is quite tall comparatively speaking.
Now to see about their longevity/durability in use.
May replace other lights with LEDs, but they are more "continuous use" and I don't want to blind anyone behind me, stopping and turning, etc.