Grandpa's Gun Parts has this interesting 'altered' 1898 carbine eye-piece on their website. (Check KCA Classifieds).

Mallory reports 35,000 model 1898 carbine sights were 'altered' to 1902 sight configuration. (Once again, this would have only involved the leaf & eyepiece assemblies. The 1898 style bases had become useless to the U.S. Ordnance Dept).

I trust this vendor, very much, and the eyepiece likely was identified by his grandfather, the late Joe DeChristopher.
These men have seen more U.S. gun-parts, than I ever will, and Joe certainly knew his stuff.

But, FWIW, I don't think this part was ever a model 1898 carbine-sight eye-piece.
The "C" on this eye-piece looks very large and irregular.
On checking the center "V" notch and the outside notches, they appear offset, to the right.

I believe this sight was a rifle eye-piece, that someone has stamped or engraved with an incorrect "C".

Even a very knowledgeable expert likely gets fooled, once in a while.

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