Guess I should have figured this might catch other attention and the reason I guess I mentioned it. Not suggesting anyone paint their blue only if your is blue you might want to investigate further
I would suspect a rebuild in the past resulted in blue paint.
I recall seeing that kind of features on 3rd party rebuilders over my 20+ yrs as Ford parts manger.
Originally just assumed that some past owner had rattle canned with engine paint during a rebuild or just prior owners being prior owners
That was the thought way back until we found pictures of cars on the assembly line with this followed by unrestored examples (car know to have not had their alternators rebuilt. This is a very rare finding and only a few (hipo and non-Hipo) witnessed by a number of those involved with judging over the years. And one of the reasons its mentioned in the judging rules