...useful for those investigating the option of factory Triumph rider backrests and 'Dual seat, Longhaul Touring' for Std, Classic and Roadster models. NOTE: This is not the later R3Touring model version.
The Dual seat is available with
Seat, Dual, Backrest Kit A9708164;
or without
Dual Seat Kit, Classic A9708059 the square post hole for the
out of production and out of stock rider backrest that was always sold separately (A9708158).
As stated by CanberraR3 earlier:
"There are 2 numbers under the dual seat without backrest - A9701163 and A9701164. And on the one with backrest it's A9700186."
The part number for the whole backrest version kit that includes the seat, rear mounting bracket and plug, but without the rider's backrest itself is A9708164.
The rear mounting bracket that is not essential is T2301985, it usually comes with the seat kits but is separate to the seat itself.