What you have are definately western coachwhips. Easterns, depending on where you get them from, have a little or a lot of black in them. They usually have black around the head and first third to half of their body, with the rest being a light tan color. Occasionally, you'll get near-black, or all black eastern coachwhips, which are glossy black from head to tail. Some even have smatterings of red around the tail, very pretty animals. Anyway, post pictures of the easterns once you get them!
Kevin