int the year of Manufacture,I can say that you have a Mossberg model 500AB that was made for western Auto by Mossberg.The model 500 series of shotguns were made from 1962-1998.The value of your shotgun will range in price from 85-200 dollars depending on overall condition and a good bore.
It is a Mossberg 500AB and they made it for Western Auto under their revelation name. So all 500 Mossberg parts are compatible with the gun. I hope this answer helps you with your question.
From what I have read so far it was made by mossberg. This is based on some articles I found doing a basic google search of the firearm name and serial number.
Proofhouse.com has a store brand chart.