Just repeating what everyone has stated, the 2004-05 (some 2006) Quest may be plagued with the timing chain issue. The heart of the problem is this engine has a tendency to burn oil and in some cases leak oil. If you extend the oil changes beyond the recommended OCI (3,750 stop and go; 7,500 highway), your Quest could be a quart or two low and you don’t realize it. I just changed the oil this weekend on my 2004 Quest (137k miles). I normally change it between 4500-5500 miles but this time it was 5800 miles (wife never told me the maintenance reminder went off). I noticed the van was noicier at startup. When I drained the oil, it was noticeably low; I estimate about 1 quart or so. After the oil change, the van sounded much smoother.
My point is watch the oil level in your van. If you are having the rattling while driving, it is likely too late. But if you aren’t having issues, keep an eye on your oil level.
Here’s a link to a discussion by a Quest owner who fixed the timing chain rattle with a $67 part. As far as I know, his van is still going strong: