87 mustang radio

friend of mine just got an 87 mustang, and the radio was all torn out, i can figure it all out, but i was just wondering, is there any type of amp i have to take into consideration, or is it just straight wires to each speaker and from the fuses, etc. all the wires were cut, not harness also, does anyone know the wiring, like which color wire goes to what, that would be very helpful