18 SF seat

[mikeyk]

This is the seat in my 74 18 SF. First of all, I understand that there was an "optional" seat available for this model but I don't know if this is it or an aftermarket product. Anyway, without cushions it's very uncomfortable, and I'd like to find cushions. If it is the original option seat, I'd like to find out if anyone else has had to replace or restore their cushions.
I see that there are aftermarket products available for boat seating but none of them have dimensions available.