There is a 48" 72CK-0-48 on ebay. It was sold 2 weeks ago for 240$ and now it's been re-listed. I know you will have to re-pitch to 54" and re-use your bolt and spacer, but it might be a good deal for you anyway...
http://cgi.ebay.com/ebaymotors/SENS...439QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
