would it be necessary to change the clutch and flywheel when replacing the gearbox,the car has now done 92000 miles,and as far as i am aware the clutch has not been changed.

 

Yes most definitely get a new clutch! If you've no idea if the clutch has been changed or not then - whilst the gearbox is already out.- it's false economy not to

You don't have to spend a bundle on a clutch kit either.

Just get the flywheel checked over by the garage for condition of the ring gear/warping/out-of-round etc. If all within spec., then not necessary to replace. However if they're cheap (don't know ), then makes sense to fit a new one too...