Tail light is finished. I cut a sheet of polyethylene sheet to fit the reflector area for the old bulb, then drill holes in a spacing pattern. I then soldered one resistor onto each positive LED leg and each negative leg to a common ground for each mode set.
The result is just as bright as the original bulb, albeit slightly more directional in focus.
The array of 32 red 3mm ultrabright LEDs consumes 9.6 / 3 watts instead of the original 21 / 5 watts.