try these [BAX9S,H6W] 6w OSRAM Ultra Life Sidelight Bulbs 12v [64132ULT]
They claim 3x life, on the osram website i think standards are about 500hrs use and the 1200- 1500.
Or stick leds like i have and they haven't gone since, i dont think they wear out it think they blow maybe because of voltage spike ?? just athought as i have never replaced so many side light bulbs since being an alfa owner. Its a good job there so simple to fit........ just like all the other bulbs...
I dont know if any of you have considered these, ebay 281196655898 (LED 5W SIDE LIGHT RESISTOR NO ERROR BAX9S H6W FREE CANBUS OFFSET PINS T10 501)
these cables convert from the h6w to the more common 501's they have a resister built in to allow you to chose from a wider range of LED possibilities.