What's your preference, the push button 4WD or the stick 4WD? I'm looking at a truck with the stick 4WD and at first I said no way, now I'm not so sure. Here's the 2007+ NBS 4WD rotational shifter/knob. Here's a 2012 4WD manual floor-mounted shifter. Looks like it's possible to purchase the button components for older Silverados. Maybe NBS as well? Looks like you can also purchase the shifters as well. I wonder how hard of a conversion it is?