If you're not going lowered (you posted in the lowered section) and don't care if your track width gets screwed up, you can get the 4WD rear axle. It's wider than the 2WD axle, by about 3-4". Worthless for a lowered application.
I'm pretty sure the "NBS" (GMT800 and really anything newer since they're all 6 lug in half ton) is wider as well, even in 2WD, just don't have the measurements handy.
The axle you want for the most direct swap is from a GMT400 (1988-1998 body style) C2500, meaning 2WD, and light duty (7200lb. GVWR) that is the 6 lug rear that is the correct width for swapping into a 2WD 1500. It's not a simple bolt-in but there's plenty of threads already on it...
Richard