I opted for a manual model given how little it gets used.
http://www.crlaurence.com/apps/contentloader/default.aspx?content=www.crlaurence.com/adv/autoproducts/index.html
I can't remember who I had install it. I will look up the paperwork later, but it was here in Tucson for around $400 if I remember correctly. The factory non-powered slider was going to be almost $800 if I remember correctly. Powered was even more. There was also conflicting information from different vendors about whether I could even put the factory slider manual or power in my truck.
Here's an update on the slider window replacement for my Silverado 1500. I found Metro Auto Glass Inc. in the Yellow Pages (Portland, Oregon). They are a mobile service. They came the next day and installed a nice Pilkington privacy-glass slider on my truck. $225 parts and labor, w/ a one-year no-leaks warranty (that's a good thing to have here in Portland). I thought the price and service was quite good, FWIW.