Agree with @Speed2Sea Ebay will bring market price, no reserve auction. If you have any papers or receipts that would help but not necessary. Good focused closeup photos from all angles will help. Honest description of condition impt don’t make any exaggerated or false claims. It is a gold-capped Seamaster Deville Automatic Watch from 1960s , looks original in good condition with some signs of wear , if you get serial number we can date it further.
If you can get it opened by watchmaker and take focused pictures of movement showing Serial number on movement, and inside Caseback showing reference number that will increase return. I think this is a front opener case need watchmaker to open don’t try prying yourself.
Do not pay for service if you are selling. Not worth it. Say service history unknown, one owner watch belonged to my …..
good luck.
Most of us would say “Nice heirloom “ and advise keeping it but that is your decision of course. It might bring 700-900 USD at auction
