As radios that emerged in the mid-seventies, the Drake 7 line was a hybrid implementation that bridged the sixties radios that were tube based in aluminum cases, and the future designs that were more heavily IC-based.
LEDs were not so common, or inexpensive at the time, so for dial lights the conventional automotive type 53 incandescent bulbs with bayonet mounts were used. These bulbs were frequently used to backlight automotive instrument panels, and combined with the dark blue film on the back of the S-meter and VFO dial, these gave the Drake 7 line its unique appearance.
As these kinds of bulbs are no longer being used in the automotive industry, it is getting more and more difficult to find them. As a result, many are producing replacements for incandescent bulbs using LEDs. I bought some from Amazon a couple of months ago, and finally got around to installing them today. I was anxious to see how they would look compared to the incandescent bulbs.
I am pleased that they worked as advertised, but I think I might have to find some way to diffuse the light a bit more, as there seem to be hotspots in the pattern of light they emit, and they are a bit too bright.