You could also use a swaybar off of a 2wd Suburban or Tahoe.
That's what I did to mine. $50.00 wrecker find off of a Suburban, including the hardware. Had to drill 2 holes on each frame rail, & one in the mounting brackets to sit over top of the big rivet in the frame that's in the way.
The rear ends that have sway bars, are specific. It mounts to the rear housing with integral mounts. I used 3" heavy duty, extra long muffler clamps. Similar to the pic that Norcal posted.
The factory bars are not that large, but they do make a difference.
I also have an aftermarket rear bar, which is larger than the stock one. (another wrecker find) I've switched the bars back & forth between the trucks, & I've found that the aftermarket one works better on the 2/4 dropped truck than the factory one, probably due to the taller center of gravity. The aftermarket bar on the 4/7 dropped truck made the truck a bit 'tail-happy' in some situations, such as when HARD braking in corners or over stutter bumps & railroad track crossings.
One thing about the aftermarket bars, such as what Norcal has, is that you can buy front & rear bars in matching sets. This would probably be the solution to the 'tail-happy' prob that I had with the aftermarket bar being used in conjunction with a stock front sway bar.
I replaced the rubber bushings for the bars on both trucks, front & rear, with urethane.
Suburbans with a rear sway bar have a smaller front bar, than if the truck came with a front bar only.
These things have made a HUGE difference in the handling of both trucks. Don't know why the factory didn't just make them standard across the board.