This kit supplied is for the 3 Rail 3 Synchro gearbox transmission for the Triumph Mk1, Mk2, Mk3 3 Synchro Models, and the Triumph Herald Gearbox 3 synchro. 1 x Gearbox 113230 Lay Shaft 3 Synchro. The listed item featured is the overhaul rebuild and repair kit for the Triumph 3 Rail 3 Synhcro Overdrive Gearbox.