"How to" Series
Modifying the rear LED headlight: Steps 1 - 5
Rear LED headlight
Step 1 - Measure from the base of the LED along the leads 1/2" and mark both leads with a Sharpie pen.
90 degree bend
Step 2 - Use a pair of flat-jawed pliers to bend the LED so that it forms a 90-degrees right angle to itself. (Although where you make the bend is not as crucial as with the front LED headlight, I place the left side of the jaws right where the flat area on the LED leads starts.)
Trimmed LED and 1K resistor
Step 3 - Cut the LED to length (See Step 1) and trim a 1K resistor so that its leads are ~1/4" long.
1K resistor soldered to LED
Step 4 - Solder the 1K resistor directly to the cathode* (-) side of the LED. Or, solder 1" long pieces of flexible 28/30ga yellow wire to the resistor then solder it to the cathode. (The latter option gives you some flexibility if room gets tight inside cab during assembly.) Insulate any soldered joints with with a piece of 1/16" OD heat shrink.
*FYI: Although it really doesn't matter which lead on the LED you solder the 1K resistor to, I like to keep it on the cathode side for consistency.
LED wired for rear headlight
Step 5 - Paint the base rim and back of the LED with black paint (e.g. Pollyscale Engine Black) to eliminate any light leakage. Let paint dry overnight before press fitting LED into the light tube.