As found on service sheet 355 for the sound version and 431 for the standard version.
Hornby X7516 Genuine Spares Princess Royal Class Loco Gear Set NEW
Hornby X7349 Genuine Spares Dummy Pony Wheels & Axle For Red Class A4 NEW
Hornby X7217 Genuine Spares Royal Scot Chassis Bottom Wheel Retainer 2017- NEW
Hornby X9160 Genuine Spares Brake Rod & Small Loco Screws Parts For Class 8F NEW
