Assuming z-71 means 4wd, I'd guess anywhere from $4000-8000 depending on exactly how clean and well taken care of it is, and how quickly you want to sell it. I had a 2006 crewcab 2wd with 85k miles and it was all i could do to get $8000 out of it 2 years ago. Miles are going to hurt you more than anything, but the better you clean everything, the more you will get for it. And I don't mean just vacuum it. Really detail it, make it look like new. The best way is to take pictures, then analyze the pictures and things will stick out. Address those things. Also, when you post the ad, take pictures detailed pictures that show how clean it is, and put lots of them. People who want to pay good money for things want to have a good idea what they're getting.