trunk wiring

I bought a used 95 cougar and in the trunk was a wiring harness not connected. i saw the same cougar at a yard to get some parts and that same wiring harness was connected to some type of computer box that was mounted on the top near the rear seat wall. What is it and can i get the one from a different car to put on my cougar or do i need a new one?

I bought a used 95 cougar and in the trunk was a wiring harness not connected. i saw the same cougar at a yard to get some parts and that same wiring harness was connected to some type of computer box that was mounted on the top near the rear seat wall. What is it and can i get the one from a different car to put on my cougar or do i need a new one?
it could be a stock audio amplifier