Recent Find Altered Carbine Cartridge Box

[Kansan]

Recently purchased this cavalry carbine cartridge box from the Horse Soldier that has a couple of interesting modifications. First, a small, unmarked oval plate has been attached to the front flap. The vertical belt loops on the back of the box have also been cut off, suggest possible use on a sling. There's a faint maker's mark on the inner flap, all I can make out is "Makers" and "New York". Thinkiing this box might have been reissued to a militia unit in the early Indian Wars period, possibly one using Spencer rifles. I'm interested if anyone else has ideas about this one or has a similar cartridge box.

Reverse of the plate.