Newer MTH Premier observation cars have a stamped bracket to hold grain of wheat bulbs next to the markers and drumhead. Older cars rely on stray light from the overhead bulbs to illuminate the markers and drumhead which doesn’t work well.
When replacing incandescent lighting with LEDs on newer cars, I have inserted 3mm round top LEDs in the rubber grommets on the stamped brackets. I also tape an LED to the bracket for the taillight. I’m pleased with the results.
For older cars, I decided to make a bracket for LED marker lights using 18 gauge solid coper wire. The side markers extended inward to the middle of the car to try to catch ambient light. I broke off part of them so I could shine the LEDS on the end. The 18 gauge wire is malleable enough that it is easy to shape to the car and to wrap around existing posts. It’s stiff enough that once I hold it in with some hot melt glue, the lights will stay where they belong. Probably not the first time it’s been done, but it’s the first time I have done it so I thought I would share.
Here’s some pics of the stamped bracket and the copper wire bracket.