So,
sick of not being able to see what's behind me, I set out on a quest for the
"last word" in reverse lights.  I have a Fenix flashlight (the L2D) that
uses a cree led, so I knew that these led's are ridiculously bright, and I
wanted to find a 1156 socket mounted version of the cree to use as reverse
lights.  I only found one place selling them:
http://www.besthongkong.com/product_info.php?cPath=10_67&products_id=522

They are very pricy, but VERY BRIGHT!! and should last forever, since they
are leds.  They also consume much less power than the stock bulbs, at 1w, so
there are no problems with overloading the circuit that can happen with
other ways of going to brighter bulbs.  I would estimate that they are each
8-10 times as bright as the stock bulbs.  I believe this is the brightest
drop-in option for vanagon reverse lights, probably by a factor of 2 or 3.

Just thought I would pass this along.

The Luxeon leds are not as bright but are available stateside.  I will
probably eventually get some of these for turn signals, etc.   The cree's
are too bright for that purpose anyways.

-Wes
'83 1.9l westy