Help needed

Hi i have a land rover discovery 2 td5 and when its in neutral and its ticking over its sounds as if there is a knocking noise coming from the gearbox and when u rev it, the sound goes faster, but when u apply the clutch it stops, also when getting into gear its really lumpy and hard , this has only happenend after i got a brand new clutch and flywheel put in to it.

I took it a land rover mechanic and he said it could be that there might not be the right oil in the gearbox and the pump is getting it tight,

Any help would really be great thanks

Welcome to the forum
Best ask in the disco section you will get more help
https://www.landyzone.co.uk/forum/land-rover-discovery.8/

As he says ^^^

If you think there is wrong oil in the box don’t drive it unless absolutely necessary- like to get it fixed or on a wagon. Disco section can tell you what should be in there, try and identify what went in.

Welcome to the forum