I have 2 Parker 45s. One is the vintage all plastic and another one, which is a current model flighter. It feels like the nib on the vintage has better sweet spot than the new one.

I tried to switched the nib units and one of them feels tighter when I screw it in. Is this okay or are they not interchangeable?

Thanks.

--Joe

They are certainly interchangeable. One of my "beater" pens is a flighter 45, new style, with a gold nib I salvaged from an old model.

Thank you. I just didn't want to break the unit. It feels tight to screw in, but it writes fine. The new 45 writes fine if you have it at the correct angle. The old 45 writes well with a wider sweet spot.

Thanks for the info.