Welcome to the Forum from NH.
Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.
I hope that you will become a participating member in the Forum's discussions.
Pics of the truck, please.
I cannot personally help you with your question; however, other members on this Forum that are much more knowledgeable than me in this area will chime in.
It looks like there is a sub within that enclosure, and if the amp is there as well, then you have a place to tap into a 12 volt power source.