coolant hose flange with divet??

[siambisg at uchastings.edu]

Just wondering if anyone has seen this.  This flange holds the MFS switch on bottom and a dual temp sensor on the top.  The divet, dime sized, is located on the outside top of the flange approx where the upper rad hose clamp goes around.  It's as if something was eating into the flange.  Also a black and brittle substance filled in the divet and created a small mound.  It's either corrosion or a past repair with some type of filler.

In any case, the relative thinness of metal at the center of the divet makes me nervous about putting it back in.

George S
'88 90q