Per Qarl - "They work for the flashers too, but you need to put a resistor across them.
I no longer sell them."

The bulb is - BA7s -and can be bought at http://www.superbrightleds.com/

I bought one in white - just to see if it would work - it does - I would say not brighter - meaning it does not illuminate more area - but is obviously whiter.

I replaced my bulbs and would concur that they are not any brighter, but definately a bluish tinge rather than the old yellowish tinged light. North Hollywood Speedometer does a LED conversion on the guages that is brighter, but is much more extensive than just replacing the bulbs. I think they charge about $300 for the conversion, but it does work well I've been told.