There's a couple sets on ebay that are about ready to end with no bids yet, they are the large truck,bus type but chrome, usually the chrome ones were on fire trucks, look at his other auctions for the other set, starting bid at 15 and 20 bucks. These might work good on the rear but due to there large size I doubt you could make them work on the front.
http://cgi.ebay.com/ebaymotors/ws/eB...tem=2452223763