Best factory Triumph Dual seats for Roadster/Classic/Standard are either the:
CLASSIC TOURING SEAT - DUAL A9708164
Shown with ADJUSTABLE RIDER BACKREST A9708160
OR the same Classic Dual seat version without a hole on sale now in the USA on this forum.
Check that he has the rear mount spike bracket, but it is not really required to use the seats anyway.
SOLD Triumph Rocket III Classic dual bench seat off of a 2009 Classic. Excellent condition. No rips. No tears. No blemishes. This is the black shiny seat, model number A9701163/A9701164. Dimple shown in photos was a passenger backrest leaning against the seat, the seat had not gone...
DUAL SEAT KIT - CLASSIC A9708059
These seats with post hole and Triumph logo removable bung are still available in Australia WITHOUT the Rider's backrest. Aftermarket Rider's backrests like
Utopia from USA can easily be made to fit.