i like older guns and always check serial numbers and proof marks. the remington society page has good info but its not always correct.
it will give you a start point but at times, its way off or completely wrong.
the best and most reliable way to get a manufacture date, original configuration or other data is to call remington.
better still send them an email with make, model, serial numbers and any questions you want answered and a tech will get back to you.
it usually takes about 2 days. you can contact them from the remington website at the "contact us" link.