The Chevy Longhorn was an 8-1/2 foot bed, it had a 6” extension at the front and a 6” longer wheelbase. They had wood bed floors.
The Ford F-350 Super Camper Special didn’t have an elongated bed, it had a longer wheelbase (even longer than the Longhorn) and a special standard-length 8’ bed with the wheelwells further aft. It had the spare tire behind a big door in the side of the bed and was the only pickup truly designed for camper carrying. They even came with a slide-out back bumper and front & rear sway bars.
All the makers used to offer 9-foot stepside boxes. They made up for the extra volume of a fleetside.
They used to call them “grain boxes”. They were a lot easier to shovel stuff out of since they were straight-walled. They all had wood floors and were much tougher than sheet metal.
You used to be able to order a wood floor at extra cost in a fleetside too.
They don’t make ‘em like they used to.
It’s too bad they’re gone, they were actually a lot more useful overall.
None offered 9-foot fleetsides.