Still curious as to the replacement problem for the parking light and the problem I have with it consistently burning out. ANy ideas?
Have you checked the voltage at the battery with the engine at 3000 RPM to make sure a faulty VR is not causing excessively high voltage.
There are 12 volt bulbs meant to run at 12 volts and there are "12 Volt" bulbs for automotive use which are really rated for 14 volts but you seem to be using the correct bulb. It's in the nature of low wattage bulbs that the filament is more fragile. A higher wattage bulb may fair better. I've only ever used a 10W or 20W halogen bulb as a daytime running light and they last me for years. When the current one fails I'll look at what high power LED's are available for the Ba9s fitting