http://www.pioneerelectronics.com/pn..._36629,00.html

several companies make double DIN head units specifically for GM vehicles.
the Pioneer above doesn't have knobs,but it has a very simple layout and a display that's not too busy.pretty much any double DIN head unit you find won't have all the latest features or high end technology,but i don't get the impression you care about that anyway.any of them are still lightyears ahead of your stock unit in performance regardless.it lists 45 watts max power-probably 20ish RMS per channel.that's WAY more than what you're working with now.retail is $250 on the above pictured model.that head unit and a decent set of front speakers......i think you'll be thrilled for around $300 if you do the install yourself.
knobs are making a comeback.many manufacturers are incorporating knobs into the units for volume controls.the main problem with a single DIN unit is that install kits for your truck look like crap.i'd try to stay with the GM specific HUs.
chris