You're probably after the guide and o-ring set, but here's a complete breakdown. Each part can be looked on Google, so you can be sure about what you're ordering.
54000 M-Chassis Aluminum Damper Set (4 pcs.)
53334 Low Friction Damper V Parts (2 pcs.)
9808169 Damper Cylinder (2 pcs.)
9808170 Piston Rod (2 pcs.)
9808171 Coil Spring (Medium, White, 2 pcs.)
9808172 Coil Spring (Hard, White, 2 pcs.)
53333 Touring Car Tuned Spring (Short) (2 pcs.)
53572 TRF Damper Piston (2-Hole, 4 pcs.)
53573 TRF Damper Piston (3-Hole, 4 pcs.)
53574 TRF Damper Rod Guide & O-ring Set
53576 TRF Damper Oil Seal
53577 TRF Damper Urethane Bushing
9804153 3x2mm Spacer
9805611 5x9mm Ball Connector
9804205 5mm Ball Connector
9805240 3mm O-ring
9808077 2mm Shaft Guide
No. From the
TCS Racing rules page:
"Tamiya internal gears only. Aftermarket idler and spur gears are not legal."