The car has never had a plate on this or anything as far as I know. This is a coolant port right? I've never seen anything leak from it though, so what gives?

87 turbo 2

Also the turbocharger appears stock, it has that little star like symbol near the top that the stockers have

 

That might be the fresh air supply to the cat. In any case it looks like it's connected to the ACV area. Personally I would block it off for consistency and to inhibit internal corrosion (as you can see it's already started).

 

Feed for the split air pipe. Yes.

 

yup. coolant line is right below it...

 

Thanks, had them mixed up