The Rocket Classic seat is the one without the provision for a back rest. The Long Haul seat was basically the Rocket Classic seat with a provision for an accessory back rest.
It bothers me that Triumph has been slowly dwindling down the accessories for the Rocket Standard/Classic and Roadster.. No summer screen, no windshield lowers, all the seat options are gone except for the dual gel, the leather tank strap with pocket is gone. Even looks like the optional Oil Tank emblems are gone.. I love my "140 Cubic Inches" on my oil tank. Triumph even used to sell custom body kits with flames in various colors that really set the bike off..