Four 68 300s need information

I recently picked up a few 1968 300s. I love all original cars and hope to get my cars as close as I can. I hope a 68 guru can help me get the info I need to restore them the best I can.
1. The rear light panel around the tail lights on some cars are silver. some are black I'm not sure what's right or if there is a way to tell. I don't see it on the fender tag or build sheet.
2. I also have a weird mark on the bottem of 2 of my build sheets saying "31 Los Angeles DLR show" is it a...

Four 68 300s need information
Author: Wojtek