What year is your 6000?
You may or may not be able to add discs to it. I know on their new bikes you need an adapter for the disc mount. Don't know how far back it'll work. Check your local Trek dealer for input.
Can you take a picture of your bike and it's condition?
That would help immensly!
__________________
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming, "WOW, What a Ride!" - unknown
"Your Bike Sucks" - Sky Yaeger