This item is mounted on my truck firewall between the battery and the starter. On the inside there is a slotted fitting.
I am wondering if it is a battery cut-off.
Thanks,
Probably takes a CAT key. https://www.ebay.com/itm/CAT-Caterp...118819&hash=item41ca5cdffb:g:COsAAOSwinVZsyYr
Bob