lol i love these threads
there could be so many different things causing a rattle.
it could be something as bad as big end bearing to something as simple as a tensioner.
the ONLY way you will know is to get a specialist to have a look and diagnose the problem.
the problem with this and other forums is some people know what they are talking about and others just guess and repost things they have read which may or may not be correct.
TAKE IT TO A GARAGE END OFF!!