Yeah, the smaller shackle hanger brackets at the corners are bolted on to the frame while the larger main hangers near the center are riveted on with large rivets that Ive never seen come loose. Also the outer tab of these are welded. Anyone who has tried to remove a main hanger can tell you how "attached" these are and not gong anywhere. I ground down both rivets below the surface and used a sledge hammer and had a hell of a time getting one rivet out. A plasma cutter is the way to go.
If your Jeep is driving bad with death wobble, It should be other issues than the frame hangers. You front left one is sandwiched between the frame and your steering box brackets so if its loose, so is your steering. It should have 3 bolts holding those brackets to the frame with no access to the top you mentioned. A picture of the described area would be helpful.
1975 CJ-6 1983 CJ-8
1986 CJ-7 Laredo 1986 TJ-7 Trail Jeep
2003 Inca Gold TJ Rubicon