Unknown wiring and electrical components

[smokinstang70]

I have a 71 c-10 that I am currently redoing... this is my first full restoration. I have two electrical components and associated wiring mounted on the firewall that I have no idea what it is or what it does. The wiring runs to nothing and I can't find any info on what it may be. Here is a picture of the installation. They are mounted on the firewall just to the right (forward looking aft) of the brake booster and main harness feed through.