Check these out......
Haven't gotten to them yet myself ($$$) but they seem powerful.
I believe they're used in some of the newer bus and truck tailights.

http://netdisty.net/ds/aut1157/

aljordans

> From: Paul Mayfield <paulmayfield@EARTHLINK.NET>
> Reply-To: Paul Mayfield <paulmayfield@EARTHLINK.NET>
> Date: Thu, 4 Apr 2002 16:29:10 -0800
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: 50 Watt TL Bulbs
>
> I remember seeing an LED taillight unit
> that fit into the standard bulb socket.
>
> It was a generic light bulb replacement.
>
> ANyone know where to find these???
>
> Paul  '87 westy
>
>
>>
>> --- Chris Stann <ChrisS@INFORMS.COM> wrote:
>>>> Forgot to mention that I went and got six 50 watt
>>> tail light bulbs for
>>>> the 87 Westy <snip>
>>>
>>> Ditto!  Same here!  They're great!  I think everyone
>>> should at least
>>> consider the upgrade.  Ralph Nader would agree!
>>>
>>> Chris.
>>
>>
>>
>> Uh I think Ralph Nader would opt for LED-bulb tail
>> lights becouse they last for decades. LED's will soon
>> be taking OVER the WORLD! Until then Ill get the 50
>> watt TL bulbs
>>
>> Phil