my gear box seems to have a problem - when i put it into reverse there seems to be a clunk sound (not always) when i lift off the clutch - it also sometimes happens in second?

For starters, what car is it?

sorry i'm new to this its a fiat stilo - about 5 years old

Not familiar with that box. (Best posted in Stilo section.) But I'd think it's as likely to be clutch related as the gearbox (how many miles has the clutch done?).

You might check the clutch fluid level (unsure if it's a seperate reservoir from the brakes on those cars) and the gearbox oil level (use FIAT recommended gearbox oil).

Sometimes a clunk will indicate a contaminated clutch (although it's not unusual hen selecting reverse, no syncromesh) or that the syncro is on its way out.

thanks very much for all your helpx