Challenger hood scoop insert drain trays

[1970A-66Challenger]

I purchased these to replace the ones missing when I bought my Challenger.  What are the correct fasteners and gaskets to use when installing them?

[7E-Bodies]

I'd give @MoparDave a shot at this first.

[headejm]

Mine are original to my 1970 Challenger. They are riveted on. There is a rubber-type seal between the two pieces. Mine haven't been apart so I'm not sure what the seal looks like. 

[MoparDave]

I purchased these to replace the ones missing when I bought my Challenger.  What are the correct fasteners and gaskets to use when installing them?

that particular gasket is not available from what I see. I would get some think rubber material or use foam tape and cut to fit.

[Scooter]

Bit OT, other than aesthetics is there a reason to have the blank off plate in there? A bit more cold air getting to the intake seems like a good thing. 

[YellowThumper]

Bit OT, other than aesthetics is there a reason to have the blank off plate in there? A bit more cold air getting to the intake seems like a good thing.

Back in the day they were daily drivers in all sorts of weather. Without them a significant amount of "weather" would enter engine area.
These things now are mostly fair weather cars so on or off would be your option.