Doran:
I owned a new 1982 SSV 164 with a mercruiser 120 I/O. It was a closed bow, but the same otherwise to this 168.
The rear seat was hinged at the top of the seat back to the boat. The bottom of the seat back was hinged to the seat bottom. The seat bottom sat in a wood frame. They used small blocks of wood on the underside of the seat bottom to keep the bottom cushion from sliding forward. You would lift up the front of the seat bottom, slide it forward a bit, then lift into place. there were small teak wood blocks mounted on the inside of boat to support the bottom of the seat back in a position parallel to the floor. Then you would fold down 2 aluminum legs with plastic caps (similar to a card table) and rest them on the boat floor.
There was storage within the framing that was mounted to the floor, that would support the seat bottom section. The framing was wrapped in vinyl. The floor inside the framing was the same floor and carpet as the boat floor. It was very simple to operate. I didn't use the sun lounger position very much, but it sort of looked neat when only 2 people were in the boat. It sort of converted the boat into a 2 seater. What was nice about it, was that after you spent the afternoon boating and were back into the garage at home, you could place the rear bench seat into the sun lounger position, and it would help with drying out the boat. We used this boat for a lot of water skiing with friends, and the boat always came back with wet carpet.
Please notice the rear hatches on each side of the engine compartment. Each were fiberglass, insulated, drained to the exterior of the boat. They would hold 18 cans of beer each side. Tom Stibbe