I would like to start by saying that I'm sorry for your loss.
If there aren't two letters on the left side of the barrel up near the receiver, you'll have to call Remington and ask them to run the serial number. And even then, the barrel may not be original to the gun.
I found that emailing them didn't get an answer when I recently asked when my old 870 was made.
But had an answer within 3 minutes of picking up the phone with a month and year.
Retail value is a lot harder to guess about. It depends a lot on what kind of condition that it's in. Also the 2-3/4" barrel chambering is somewhat less desirable from a shooters perspective. The newer ones have a 3 inch chamber.
Also depends a lot on the barrel/choke, bolt, what kind of furniture the gun has, etc
There's no real way to guess, but a brand new wingmaster express can typically be found for under $400 rather handily just to give you a starting point. There are some wingmaster versions that can get upwards of $1000. But the express is generally the more "mass produced" variant.
Here is the info that Remington requests you have available if you call:
In order to assist you with identification of your firearm, we need the following information:
•Is it a rifle or a shotgun?
•What is the action type, rolling block, slide or pump action, auto-loading, bolt action, or lever action?
•Can you determine the caliber or gauge?
•What are the patent dates on the gun?
•What are the exact markings referring to Remington?
•Does it have a serial number and if so, what is that number?
Please provide us with the above information along with a brief description of the gun and we will furnish to you the information that we have available. You can send this information to the following:
Remington Arms Co., Inc.
PO Box 700
Madison, NC 27025
Fax : 336-548-7801
Contact Us or call our historians at 1-800-243-9700, Mon-Fri 9am-5pm EST.