I am going to guess that you have a 1970 DURACRAFT 1542 or 1442 MV, forget how long you said the boat is.
Why Duracraft? The gunnels of the Duracraft, were made to hang their accessories on. consisted of a slot, fore and aft and an oval folllowing that towrard the inside of the gunnel.
In that one picture if you will look at the top front of the middle bench you can see the bracket that Duracraft came out with so you can easily add and remove the seat. Later there was an after market for the seat bracket. Go to Bass Pro site and call up part number 38-567-827-00 , under boating accessories, and you will be able to see and understand how it works better than trying to figure it out from that picture of the boat.
War Eagle boat are made by I think its now the 4th Generation of Wards and you will notice that on the flatbottom boat they have basically the same type of gunnel (has been changed just a bit, but still basically the same) as well as see the seat brackets mounted on the front of the bench seats.
The Duracraft of that era are great boats. I have been using a 1986 1542 mv since it came out, and I have had no problems or complaints with it. If I were going to buy a new boat today, it would be a War Eagle, considering its still the same family building them as were the old Duracraft.
Let me know if you are still in doubt and I will take a pic or w of mine and post them later