Something else I though about since it finally gets through my head that your talking about the knuckle joints. Can't sleep tonight, so thought I would post this. I hope it makes sense, but it's what I thought I might try when all else fails.
1) Joints are junk anyway. How about some extreeme and fast heat on the cap of the joint. The rapid heat with associated expansion might help break the cap loose from the yoke that will not heat as quick. Pre-heat flame of a cutting torch (to cherry red, not too hot) or just lay a "rosette" type bead right on the cap. Followed by rapid cooling before the yoke can get too hot from convection.
2) Once you think the caps should be broke loose, spray it down with penetrating oil while still hot, but not hot enough to burn the oil. Now support the yoke and smack it on the caps sort of like you would do to seat the clips when installing, but the reverse. Ideally, if you are smacking down on the top cap from above, you would support the same ear of the yoke that the cap is in. That should help break the clips loose from the yoke, and maybe from the cap too.
3) Now go back to trying to drive out the clips.
4) If it still won't cooperate, try a small sharp cold chisel and break the c-clip retaining lip off the inside of the cup, then pop the clip inward away from the yoke.
Obviously a press could be used to help break things loose if you can figure out a good SAFE way to support the yokes, just don't bend the ears. But the impact of a hammer may work better. Might even dry an impact hammer on the caps. The caps are also very had and I've seen them fracture, so an impact might work in that respect too. Again, be careful not to damage the yoke.
I have stuff get stupid hard many times and in many ways. If the obvious approach does not work, and it often won't when dismantling a wrecked/broken/damaged area of a vehicle, it's time to get creative.
