remington:  Many of the 1898 Carbines were "up-graded" to 1899 Carbine configuration when they required overhaul.  These 1898 Carbines will be found with the long for-end 1899 style carbine stock.  I imagine 1896, 1901, and 1902 Carbine rear sights were all utilized on re-builds (with appropriate hand-guards).  The re-built Carbines are legitimate issue arms.  Just not as desirable as the unaltered version.