There is a 1873 Sharpts checkered Steel Butt plate on EBAY For $99. It looks very nice. check it out.
EBAY No. 353505069974.

Don't think it's a Sharps.
Looks more like a Niedner.
I'd like to know why the guy listing it says it's a Sharps.

Seems I've seen scratching like that before on the back side. Maybe Kimber of Oregon.