Does anyone know what goes in this spot on the firewall?

I'm putting my Dart back together. Its a 1972 Dart Swinger with 318 & auto trans.

My dad and I do not know what goes in this spot. I've searched google for reference photos but most darts I'm seeing dont have this hole. Some seem to have a relay or something bolted in that spot but I cant tell of there is a hole behind them


Here is mine. Circled in red is the spot I'm talking about. There is a hole and 2 dimples to the right:
IMG_2407.jpg


Like most I've seen in google images.... Just 3 dimples there but no hole.
167036_b_887c13ffb1decd00.jpg


this one has the the same hole with 2 dimples but it appears the dimples had screws in them at one time:
1972-dodge-dart-swinger.jpeg

This one has some kind of relay bolted there:

1972-Dodge-Dart-4-630x390.jpg

Any help is appreciated. Thanks in advance!