I have a box with amp, stock radio, and I cant find the RCA output converter so that I can run a sound system in the car. Anyone have an idea or know where I need to buy whatever it is I need? I don't want or will not cut into my factory harness.

it's called a hi/lo converter, and any stereo shop will have one

This. Some places call them line output converter as well. You will need to cut into factory wiring for signal from the speakers.

I did a sub and and amp install on my X that had the RF package...If you have this same setup all u need to do is disconnect the stock sub and splice the line output converter into the stock subs harness...it's 4 wires all together....If u need help finding which wires connect to each other I'll take a pic of mine and post it up

Here's a pic of my install

Thanks guys.. I appreciate it..
No I don't have the RF package and it's sucks I have to cut into the factory wiring.. Don't want to do this.

You still don't have to cut into your factory harness...All you have to do is buy the line output converter and tap into the rear door speaker...or whatever door speaker you want and run the rca's to the trunk....I recommend using one of the rear door speakers cuz it's closer and easier to run to the trunk than the front door speakers

who cares? It's two wires and they're color coded. You can't mess it up.