Does my 8 3/4 489 case need "body work"?

Noticed a spring hanging down near the center of my differential (see foto). I guess it must be left over from when a previous owner installed an 8 3/4 rear end (open, 2.93, 489 case) in my '65 Formula "S". Probably used to hang on to a brake line or something.

Then I noticed what appears to be a dent/indentation in the very backside of the differential (see foto--it is a little hard to see with the rust in the way). I don't think that is supposed to be there, should be just round and smooth (like a baby's bottom) right?

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