My 2000 4Runner also makes a sound like what you describe when I'm making low speed turns. I think it's probably normal. I've only noticed it in my driveway when I have all the windows open.
Go here for 3rd gen diecasts:
http://www.top4runners.com/thediecaststore.html
Tamiya also makes 2nd gen 4Runner models that are sold outside the United States. Do a search for Tamiya HiLux Surf (4Runner designation outside of US).
Hope this helps.
