LEDIndicators
Instrument Cluster / Dash
Replacing your instrument cluster / dash lights with LEDs is very easy to do. LEDs have the advantage of not burning out like regular filament lights. They also help reduce the strain on the GS's charging system.
1989 to 2000 GS500 Bulb Information
Speedometer and Tachometer = 12 volt, 3.4 watt (as per the GS500 owner's manual)
US = #168 or #194
UK = T10
*Preferably radial-aimed type LED so it shines down far enough to illuminate the trip meter/counter
Neutral and Oil indicators = 12 volt, 3.4 watt (as per the GS500 owner's manual)
US = #168 or #194
UK = T10
High Beam indicator = 12 volt, 1.7 watt (as per the GS500 owner's manual)
US = #168 or #194
UK = T10
Turn Signal indicator
US = #168 or #194
UK = T10
*You need to use a non polarised LED for the Indicator light
2001 and Newer GS500 Bulb Information
info from pbureau69
Speedometer and Tachometer
US = #168 or #194 bulbs
UK = T10
Neutral, Oil, High Beam indicators
US = #74
UK = T5
Turn Signal indicator
US = #74
UK = T5
*You need to use a non polarised LED for the Indicator light
Links
Autolumination
194 / T10: http://autolumination.com/194.htm
74 / T5: http://autolumination.com/74.htm
Superbrightleds
Superbrightleds.com has some wonderful products. Here is a link to show the different styles of bulbs mentioned above:
http://www.superbrightleds.com/mini-wedge.html
ShowBizWolf recommends these for Speedometer and Tachometer bulbs:
and these for 1989 to 2000 indicator (oil, high beam and neutral) bulbs: