Thanks for your response. I have removed the domed nut part of the assembly by filing off the ‘peened over’ end and inspected both parts. The ‘bolt’ part (with the flats) appears to be both original and in good condition. The domed nut part also looks to be original but may have been ‘modified’ hence the peening over. On re-assembly the two parts appear to assemble o.k. with the flats engaging correctly in the anchor plate. There is a gap of approx. 1/8″ between the anchor plate and the frame lug. Is this correct ? Also the diameter of the hole in the frame lug is bigger than the outside diameter of the domed nut (which is 11/16″). The result being that when the rear brake is applied the domed nut moves forward/backward in the lug and is audible. Something is not correct here. Has the hole in the lug become oversize, is the gap correct, is the domed nut part correct ? I need to get this right. Any help/advice would be appreciated. A photo or dimensions would be very helpful.