Late cab light question...

[80SPORT]

My early factory original units appear to have a special area embossed into the roof panel and the nuts(which take a 8/32 ss machine screw) welded in.
So I assume this was a spec panel for the roof marker lights.The later trucks appear to have just the hole punched and use sheet metal screws.Not sure if the factory built units with speed nuts as per the service kit.Interesting to see the engineering detail including the special sealing washers that went under the screws;I am using o rings now under the screws to seal as I was unable to source new washers.Roof marker lights were standard on R05 duallys and available on most other models -but not with Z77 Chevy Sport.They also show as available on Suburban ...but I can't remember seeing one with them.