New noise heard when starting..
 

Just last night I went to fire up the MPV (2002, 85k) and it made a rusty noise like something was loose underneath..or like something came undone and it created a rattle noise (primarily when starting the vehicle and then turning it off)....this noise is almost like wrattling 5 rocks in a small tin can. I was having a buddy do a tune up later in the week already, but any thoughts right now as to what this might be? My first thought was the starter or something along those lines since it's doesn't appear to impead the driving of the vehicle itself....but I have no real clue..

Thanks for any input or direction.

-Witt