1951
The serial number indicates Ithaca manufactured your Model 37 in 1956.
1950
1947
Date of Mfg. is 1947
1949
With the serial number provided,your Winchester model 12 pump action shotgun was made in the year 1949.
Watch Gunbroker.com - they often have barrels listed. Also you might try Ithaca Gun USA, a company that has picked up the rights to manufacture the Model 37.
you might be able to get a answer at arms collectors.com
http://www.diamondgunsmithing.com/page5/page23/index.html
Your Savage model 775A was made from 1950-1965.I am afraid that is the best that I can do.You may want to contact Savage directly to get the exact year of manufacture.
There's a list of serial numbers by year at http://ithacagunrepair.com/page5/page23/
There's a list of serial numbers by year at http://ithacagunrepair.com/page5/page23/