Wiring RCA's

[DetroitSteel88]

Okay, here is my dilemma:

I have an old DXZ855mp I am going to have installed along with all my other goodies, and I remembered that this head unit has the option for auxiliary input - via RCA cables, so I was like "sweeet!"

But, taking a closer look at it, there are only 3 sets of RCA's on the back of the unit.
I cannot find a new harness anywhere, so the "easy" solution is dead for now.

I have a custom 12" zv2 (done by SPLaudio) and an Autotek 1500 that will be using up one set.

I have one set that will hopefully be used by the Mp3 player....
Then, I have MB Quart components and rockford coaxials that need a set to be powered by an Alpine Amp.

Clearly, there is a set missing. I just hope it's not the AUX input set, because

I have: A long pair GREY in color (red, white, and black wires going into the connector)
A long pair BLACK in color (red, white, and black wires going into the connector)
and a short pair RED in color (TWO black wires, red, and white going into the connector - 4 total)

If I need any additional parts/accessories, I want to get them NOW before I drop the car off for install.

[DetroitSteel88]

and no, the manual does not tell me.