I can confirm MNSmith's assertions that:
1) Suburban front and rear bumpers are interchangeable - with a slight exception: Original Suburban rear bumpers were heavier gauge steel than front bumpers - 1/4" vs 3/16". Doesn't matter unless you're doing a points restoration.
2) Pickup front bumpers will fit front and rear on a Suburban. The REAR BRACKETS however, will not interchange.
3) 1/2-ton Suburban rear bumper brackets are completely unique; pickup rear brackets won't work on a Sub, nor will 1-ton Sub rear brackets fit on a 1/2-ton Sub. It cost me $125 to learn that last one
