What is the electrical box called on the passenger side at the end of the dash on a Chevrolet truck called?

There is a rectangular box with electrical plugs going in to it and out of it goes to the electrical harness of the truck.It is a 2001 Chevrolet 2500 4 door that someone has wired in to it some kind of alarm or keyless entry or something and has the power windows where they wont work. I need another one of these electrical boxes with the original wire harnesses but not sure what it's called.Thankyou.|||You don't know what it is or who put it there but you need another one? Sounds like a FAIL to me but good luck.|||If it is under the dash on the passenger side it sounds like the brain box.