Heater core outlet diameter

I just noticed my heater core has 1/2 and 3/4 inch outlets instead of the 5/8 I think it should be.

Do I have the wrong heater core? Or there different cores?

On this hunk of **** I have I can never tell what I have to unf@@ck because some other pole spinner cobbled it up.

So can anyone tell me why the heater core has a different sized outlet and if it is wrong?


Thanks