Your Winchester model 37a was a reintroduction of the model 37 which occured between 1973-1981.That is when your model 37a was made.
I have had several of the 410 37a youth and full value is 125 to 200 depending on condition
A 20 guage WInchester 37A youth model will go for between $100-150 USD depending on condition.
Serial # C861323
there are several listed at gunbroker.com
Between 90-200 dollars,depending on the overall condition of your shotgun and a good bore.
These inexpensive Winchester shotguns are selling for between 55-140 dollars.
The 37A was manufactured from the mid 1960's to the late 1970's.
can you tell the age of a model 37a 20 gage Winchester by looking at the serial number
50-300 USD depending on specifics
Blue Book of Gun Values
The value for a Winchester Model 37A Single Shot Shotgun with a 36" Goose Barrel is shown as a high of $154 in 100% condition, to a low of $61 in 60% condition. This is based on the 30th Edition of the Blue Book of Gun Values. I hope you find this information helpful.