What part am I missing on the taillight?

[jbach36]

On the taillight assembly, you put the bulbs in and there's a shiny silver metal springy tab that the bottom of the bulb hits to keep it secure, shown at #1 on the photo. For another bulb area shown at #2, that shiny silver tab is missing.

What would the name of that piece be and where could I get one? Without it, the bulb is really loose and wobbly.

Thanks,

1991 300d 220k