Quick question. I've got some new pickups for the Ibanez P/J in my sig. One is a Duncan QP P-pickup. The J is out of a Fender Japanese Jaguar. The Duncan has white/black wires. The J has Red/Yellow. Which one is ground on the J pickup, or does it matter. I've wired up automobiles and done some light residential electric, but this will be my first bass rewire. Also need some input on a Switchcraft barrel jack. How to wire it up properly. Thanks for the input.