Hatrock-
Be aware that the Aqua Magic Style II seems to be a little wide across the rear of the seat. Some seats, such as the one I recommend below, can slip to one side if not installed on-center or if pushed side-to-side.
I bought the American Standard 5055B.60CH. It's a slow-close unit. It's not a lot sturdier than the Thetford (I've bought both, to replace a non-slow-close Bemis that came with the coach when I bought it). Spec is
here. I like the way the American Standard lifts off for cleaning.