rmarrion, nice shotgun.
I agree with Dbl gun, I think it's a model called the "New Ithaca Double" (NID), produced from 1925 to 1948.
Here's a link that covers the serial number ranges Double Barreled Shotguns, High Grade Shotgun dates of production doublegunshop.com - shotgun gun firearm SxS Side-by-side
After the 1934 model the cocking indicators were removed from the design of the shotgun.
This model was availible in different engraving grades.The grade number should be located opposite of the serial number on the reciver, by the gauge #. It was offered in "field" grade (basic) and numbered grades of 1e thru 7e, along with the "sousa" grade (highest).
Here's a link to one that looks simular to yours ITHACA NID #2 12GA 28" - GunsInternational.com