I would start my search at numrich gun parts corp.they can be found on the web.
model 620-a
== ==
your sears shotgun was made by savage arms.There model number was savage model 96.
The savage model 220 shotgun made from 1938-1965 will bring between 40-75 dollars.
How old US a Stevens savage model 530a 16 gauge
Stevens 947y This shotgun is a Savage 940,940Y,or 940B
The value of a savage OU model 333 12 gauge shotgun depends on a couple different things. The most important of these things would be the condition of the shotgun.
Savage Stevens
Do not get any ideas
A Savage model 24 -3030- 12 gauge in good condition is valued at $500. It is a rifle over shotgun combo.
It a Savage models ... 30D, 30E, 30F or Stevens model 67
Your Savage model 775A was made during the years 1950-1965.