[wrndln]

Are you sure they are all Ford made parts? There were many aftermarket parts makers over the years (jep (sp) parts Ford called them). I suspect one or more of the parts in your picture might be repros. I have seen the same thing with crank bolts - differences and always chalked it up to repro parts. I even had one that wouldn't thread into the crank threads - I don't think Ford would make any parts like that.
Rusty Nelson