1985 Driver's Door Lamp Assembly

Was just wondering if you would know why GM and after market suppliers would not be handling the door lamp assembly for 1984-1985 corvettes?  You can buy through GM and all after market suppliers:  door panel control plate both right and left side, power door lock switches, wiper switch, as well as the bulb for the door lamp assembly - but no where can I see a supplier for the  actual door lamp assembly.  The part number that I have from the GM service manual for the left hand door is as follows:

Lamp DM & RDG In DR-LH 918255

If you could give me any help would be greatly appreciated.  I know one option is to buy from a wrecked car - but would likely have the same problem as part is plastic, and over time plastic gets brittle and breaks - but also from Canada and hard to find a wrecked 1985.

Thanks !!!!