Worn bushings weren't the cause of this problem. Likely the inner tube for the pin broke loose for whatever reason.....bad weld, loose nut, one too many pot holes, accident, etc......and it damaged the area where the tube was attached. Instead of repairing it properly by welding the tube back in place and repairing the surrounding part of the K-member, they just welded everything together. That works fine until you need to pull the lower control arm again. In looking at your photos, are you sure the pin is welded to the K-member? Maybe it's just really stuck. Either way, I'd look into getting another '68-72 V8 K-member. Transfer your I.D. washer if you like should the replacement K not have the same one.