78 SC, what is missing?
 

What is missing here, should there be a cover, there are two threaded holes that I've circled.

Thanks
Kirk
78 911SChttp://forums.pelicanparts.com/uploa...1243035139.jpg

The plastic cover

Plastic cover.

A Black Plastic cover... Triangular in shape with rounded corners.

A wing nut screws into the tag you have circled at the top of the picture.
This wing nut secure the cover. ($15.00 est for both at you local wreckers)

The bottom captive thread on the alloy bracket is not used for anything on my car. (nothing was ever there)

It doesn't have to be plastic (or, as is more likely the case, pressed cardboard). Mine is carbon fiber. Saves me the weight of a sparrow's feather back where it's meaningful...

got one if you dont find one locally.
http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/473980-fs-parts-1980-sc-track-strip.html

"The bottom captive thread on the alloy bracket is not used for anything on my car. (nothing was ever there)"

In OEM configuration there is a second wing screw (with bearing washer) that engages that captive nut (there's a hole in the OEM plastic cover that aligns with this lower captive nut). This lower, second wing screw is often lost.