While the front indicators were pretty good, the rear indicators were always weak, especially in daylight. The indicators are also set quite low so they are easy for a car driver to miss. When I'm riding I'm always particularly concerned about drivers plowing into me from behind. I replaced the bulbs several times, trying different makes, etc, but none really improved the situation.
I'd heard that some companies were manufacturing LED indicator kits for classic machines but although I made some inquiries I couldn't find a 6 volt - until now. Auto Lumination produce a wide range of LED auto lights for all types of vehicles. To my great joy they had 4.4cm 6 volt festoon globes that could slot straight into my repro Lucas indicators.
At US$9.95 each they are fairly expensive but they work! No new flasher unit, no rewiring, just replace the globe. You can see in this photo the globe comprises 3 rows of 3 LED panels. And do they make a difference?? Do they ever!
These are the old globes. They don't look too bad in the garage where it's dark, but on a sunny day they are a total washout.
The new LEDs are much brighter and will last a lot longer than filament globes apparently.
Auto Lumination are in the US. You can find them online here: http://www.autolumination.com/