David, nice fossil. If this is definitely from the Madison Limestone then it is Mississippian in age — far too young to host Rafinesquina or Strophomena. I do concur that it is a strophomenide brachiopod, most likely an orthotetidine. This article is a good jumping-off point:
https://imnh.iri.isu.edu/digitalatlas/geo/gsa/papers/gsac1p4.pdf