W210 Mirror Signal Indicator. Module? Bulb?

[Bill '90 300E]

I'm trying to find out if the mirror mounted turn signal indicator (W210 2000 E320) is a complete replacement module, if it's a simple bulb swap...or a full mirror shell replacement.

I've searched far & wide and can't find a module or a bulb, so I've finally decided to ask the guys that know.

Also, if it is the module or the bulb, does anyone have any idea where I can buy replacements?

Thanks in advance...