I'm going with Eastern and is in need of some soaks, It looks extremely dry. It amazes me that people sell turtles and can't tell the person buying it what type it is.
What's the location? I agree it's either an eastern or gulf coast. The rich black carapace could be associated with the panhandle, or it could be an intergrade. A lot of intergrades are being found and plenty are bred and sold nowadays. So who knows. My guess....it's a box turtle