clutch booster...service part?

superdukegod

superdukegod

Just had my 2006 SD in for a service with valve clearance check,mileage is 17200.Everything OK apart from I need to have the clutch booster replaced as it's showing wear.Part No;60032080000
Thought it was the sprag clutch that was the dodgy part and have never heard of a "clutch booster"
Anybody had this part replaced or in fact ever heard of it?