I think I might have found it now!
It looks like your pen may be a Parker ‘Televisor’.
They were a version of the 1930s Parker Duofold that were made in a factory in Canada, which Parker had set up in the 1920s to make pens for export to the British Empire.
The fact that your nib is stamped ‘Made in USA’ may mean that your pen’s nib was swapped by some previous owner, or that the Canadian factory assembled pens with US-made nibs.
Looking at your photos, the nib does seem to be slightly smaller than your pen’s feed, so I suspect that a previous owner may have replaced a damaged original nib.
Have a read of http://parkerpens.net/televisor.html, and see whether your pen looks like it could be a ‘Televisor’.
That all said, I am puzzled by the part of your pen that is visible between the grip-section and the threads onto which the cap screws.
It appears to be opaque, and of a slightly narrower diameter than either the grip-section or the barrel.
To me, this suggests that your pen may have been assembled from parts of various Parker pens. Perhaps by a previous owner who had broken e.g. the grip-section of one pen, and so replaced the broken part with a component from another model.
Which would make your pen a ‘Frankenpen’ or a ‘FrankenParker’. But if it still writes nicely, who cares? 🙂
Slàinte,
M.