The bolts are basically interchangeable, though there is a difference in the root of the handle. You want an 1896 bolt, which has a very short flat on the bottom, as opposed to an 1898 which has a longer flat. An original 1892 bolt (with solid guide rib) would work as well - root is like the 1896. I can see the extractor pin notch on the receiver, so your rifle has been through the 1896 modification process, saving you the expense of a very early bolt. Source for parts: Gunbroker, or Ebay.