Fire extinguisher is a great guess. Flahlight holder maybe?

The last tune up sticker in the door is from 1983 , decommissioned in 1996. Was at the insane Asylum in Stockton,Ca.


1959 3100, original 235/3 on the tree w/overdrive. Carter YF 2100S carb, 205/75/15 w/front sway bar