You can find a store brand chart at e-guparts.com that might help.
your sears shotgun was made by savage arms.There model number was savage model 96.
need a diagram of sears model 66m shotgun for takedown
Your Sears model 200 shotgun was made by Winchester.The model 1200 Winchester is the same firearm.
Depends on model and condition. It was not made by Sears, but by another gunmaker FOR Sears.
Stevens model 18D
I believe that your Sears shotgun is a Winchester model 37A shotgun that was made for Sears Roebuck And Co,.
The Sears model 200 is a Winchester Model 1200.
High Standard made the Model 75 for Sears. http://www.histandard.info/PDF/Sears%20Shotguns.pdf
It is the Winchester model 1400, made for Sears.
Your shotgun was made by High standard in 1960 for Sears. The model 21 was first introduced by Sears in the spring of 1958.
Probably Mossberg
No sn provided and there is no sn data for Sears.