The Yamaha REAR ARM & SUSPENSION has fifteen products enlisted in the schematic.
The most reasonably priced component used on the Ttr90 2004 5hnj Denmark 1c5hn-100e1 Rear Arm & Suspension is the Bolt, With Washer.
Some items from this specific schematic: Case, Chain, Washer Plate (3l6), Nut, U, Shock Absorber Assy, Rear.