I don't know about this specific set, but LED bulbs have been tried. The "regular" direct replacements (those that fit) don't draw enough current. Here's why. The stock Lucas flasher unit is made with a bimetal strip. Think of the coil you've seen inside old mercury style thermostats. In our case, as current flows, the strip heats up. As it heats it bends because of the difference in the metal of the two sides. That causes it to break the electrical connection and your bulbs go out. The strip cools, contact is made again, current flows, and it breaks again. That's how you know you have a burned out bulb. The light on the dash never goes out, because not enough current is being drawn to make the process function. .. LED bulbs cause the same problem. You can replace the flasher with a modern one though and then you'll be just fine.