diesel rattle

My 56 plate TD4 produces more diesel rattle than my previous 01 TD4. I noticed the engine cover is smaller on the 56 plate, so I have assumed this is not filtering the noise as well . Can the earlier engine cover be fitted to the latter model? Should it rattle? Does the vehicle need more time to run in? It has done 8k.

Plenty of questions to go at.

Thanks

it makes very little difference to noise levels with or without the cover,