Broken U shackle

From the pictures I am assuming that when you tried to screw the bushing out of the hanger bracket the top of the bushing sheared off. If this is the case, the bushing is likely galled in place and isn't going to screw out of there any time soon.

First temptation in this case is usually to find a huge EZ-out and try to use this to get the bushing out. The problem with this is that the EZ-out will actually expand the bushing, and make it even harder to remove. (It's already seized, do you really want to make it harder than that?)

I would put a fresh bi-metal hacksaw blade through the bushing and then install the blade into the saw frame. Try to cut a groove straight across the length of the bushing without cutting into the hanger mount. Then rotate the saw 180* and do it again directly across from the first cut. Spray the crap out of it with PB-Blaster, Kroil or another good penetrant. (No WD-40 is NOT a penetrating oil!) Once you have the two relief cuts made, you should be able to use a hammer and a cold chisel to peel the bushing inward and then drive it out of the bracket.

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I forgot to mention that when you screw the new bushings back in, use lots of anti-seize compound on them to prevent a reoccurrance. And don't forget that some of the bushings are left-hand thread!