Just fitted a pair of LED stop tail bulbs to big blue and little yeller to give the vintage charging system an easier life.

Even with a fully charged battery, putting on the tail lamp without engine running will slightly dim the neutral light.  Using the brake light 21w bulb dims it even more.

After fitting these bulbs, when using the brake light, tail light or both together does not affect the neutral light whatsoever.  The light output seems to be similar to the stock bulb.  So hoping I have more power to the indicators while braking.  They still work, but the telltale yellow lamp noticably dims under braking.

Time will tell how durable they are, but for now they seem to work very well.  To be found on Amazon.  6v LED stop/tail bulbs.