Re: STK wiring
If you mean a Stack Plus, they are not. Someone should make sure I'm not forgetting exactly, but you only use the red if you want to split coils (otherwise tape it off.) The other two wires are hot and ground (and the bare is ground.) If you assume the wires are the same as a humbucker it won't work.
Edit: but I think "Classic" stacks are different. A stack plus would have four total wires. What particular pickup do you have?