Sorry you haven't got more info yet, but I can tell you how my K5 diesel stuff is set up.
All the brackets were riveted (now bolted since I added them)to the frame, and all BUT the muffler brackets themselves use a clamp around the pipe. The forward brackets (they'd be between the cat and muffler) use a cast iron half circle piece, along with a U-bolt around the rest of the pipe.
The muffler hangs off an L shaped piece of flat metal that bolts to a bracket on the back of the muffler, locking in with a small tab so the muffler can't rotate on the single bolt. Bolted to the frame is an arm that has a square end, which contains a square rubber isolator. The L-bracket slides through the center of the square rubber piece and hangs from that.
I can't recall exactly how the last hangar is setup, but I do believe it's another riveted to the frame hangar, which uses a stamped steel half moon piece that locks into the a half moon piece welded to the hangar. There is a slot on the hangar half, and a bent "ear" on the lower piece that fits through the slot on the hangar half. Once the lower piece is in the slot, it's pulled up against the pipe, and aligns with a hole on the other side of the hangar half, which a bolt passes through, and uses a nut to tighten the two halves against the pipe. Going to go look to see if any of my pics are good enough to help you.
I would suspect a Suburban uses a similar setup than my K5.
http://dyeager535.topcities.com/partsmanual.html Check the K5 true dual exhaust pic, it's actually pretty decent.
