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My favourite bulb from Superbrightleds.com is the 194 because it incorporated a rectifier and is non polarity dependent.https://www.superbrightleds.com/moreinfo/miniature-and-subminiature-bulbs/194-led-bulb-1-led-miniature-wedge-retrofit-car/197/I usually do away with the socket and solder wires direct to the lamp, they should outlast the bike and you don't need sockets with their additional connections.If the wires have become corroded over the years they will be impossible to solder, in that case you can retain part of the old wire lugs as a soldering aid.The generator LED will not draw enough current to trigger the alternator but you can do that with an equivalent resistor in parallel. I think 20 Ohms should do it.If you are running LEDs in the turn signals you may need to modify the idiot light in the dash to prevent cross-talk, that's dead easy with a pair of diodes.Don't buy the resistors to put in parallel with the flashers, they are not necessary.
Only issue with LED on a T3 has to do with exciter current required for the Bosch alternator. The incandescent bulb passes enough current to start the rotor magnetic cycle. An LED indicator might require adding a resistor into the circuit to feed the rotor at startup.
I fitted a different version of this dash that has turn signal indicators. It's from a V50 of some sort. It is easy to tap the turn signal wires. The dash has a "brake" light that indicated low brake fluid; I rewired it to indicate the brake light was activated. I also added a relay to the low beam indicator, which I found to be an unnecessary nuisance at night; it now illuminates to warn when I have forgotten to turn the headlight on.+1 on the LED conversion.Moto
This is a V50 III dash....