It's a little hard to tell, but from the first picture it looks more like a 1928-29 windshield frame than a 30. The slide brackets on the side and the shape of the lower inside edge at the ends indicate 28-29 I think.
I agree with Randy. Looks like a 28-29 the way the lower outboard edge is shaped where it meets the cowl. A 30-31 has a different shaped cut on that metal edge.
will it work on a 30 if it is a 28-9?my buddy has a 29 coupe but it has a aftermarket alum frame,he thought this one was a 30-31,maybe a cabrolet??? thanks guys