A few z'd frame pics
I have lots of pictures of my z when I did it, in progress pics as well... Mikey's z, pictured above, is a 4in z, the one I did on my truck is a 3in z. When I finished mine, it gave me a 3in drop, no blocks, full factory suspension. I have since re added 3in blocks for a serious static drop, but if I had kept a regular factory style bed, and done the z, it would have allowed me to keep a flat bed floor, with no c notch hole in the bed floor, but still give the same kind of clearance in a different way than a c notch. Imo I think a rear frame z is cleaner than just leaving a hole in your bedfloor to clear a c notch, or even making a c notch hump cover.
Link to my z work