You would need to include the model number or name of your Ithaca firearm,along with the serial number to get the correct answer.
Your serial number indicates that your Ithaca shotgun was made in the year 1920.
Call Ithaca at 1 877 648 4222 and they will tell you.
The Ithaca Model 37R with serial number 505739-4 was manufactured in 1970. The serial numbers for Ithaca shotguns can help determine their production year, and the range corresponding to this serial number indicates its date of manufacture.
1924
Impossible to answer without the serial number
A model 37 with the serial # 10464 was produced in 1939.
Impossible to answer without the serial number.
1976 is the year
It sounds as if you have a Ithaca Crass model shotgun,that was produced in the year 1903 by your serial number.
1970
Impossible to answer without the serial number
1905