pahoghunter:  The 1896 and 1898 U.S. Krags basically use the same sideplate.  Very early Krags had some minor differences and the plates were sometimes numbered to the action.  Joe Poyer's book describes the minute changes.  Sideplates are retained by one sideplate screw.  These parts are often available for reasonable cost on eBay and gunbroker.com.  S&S Firearms (Glendale, N.Y.) also probably has these parts (in their on-line catalog).  The sideplate also helps retain the ejector pin in its hole in the receiver.