After taking the drive shaft unit apart I discovered that some of the material on the drive shaft flange was missing. The result was that the flange had moved too far into the hub and the distance between the flange bolts and the bolts on the caliper mounting has been too close.
The outside bearing (nearest the flange) was is very bad condition. I suspect that some one in the past has assembled the drive shaft unit with far too much preload or the bearing simply has gone so bad that axle has been rolling inside the bearing surface. The bearing was not rolling as it should and the flange was instead rolling on the bearing surface eating up material.
I can only guess what happens if the bolts on the flange came even closer to the bolts on the caliper mounting plate making a total interference.
I enclose some pictures of the flange showing how the material has been eaten up. A also enclose a picture of the bearing (SKF ?) were it is noticeable that the flange has been driving on the surface. It can also be seen that the head of the bolts has wear marks from the interference to the bolts on the caliper mounting adaptor plate.
