Sears sold guns manufactured by other companies under their own name. This is also true of Coast to Coast hardware store where my dad bought a 12 ga and a .22 back in the day. The shotgun is a Mossberg and the .22 a marlin. as far as I know they are nearly always the exact same gun as the orginal manufacturer sold only with a different name stamp. On some guns you will also find a stamp for the orginal manufacturer. My dad's .22 is stamped on the receiver with "Coast to Coast" but the barrel is stamped marlin.
Did Stevens make a 311D? if so I am sure that is what the gun is.
"I don't go shooting without my guns and they don't go shooting without me!"