I'm looking at a domestic flight on China Eastern in which the plane only has business and economy--no first class. When I search ctrip, it shows the cheapest premium fare as "first" and then a number of fares designated "business" that are more expensive. I'm assuming all of these fares book into the business cabin but I am missing some quirk here? I can't get to a seat selection screen (if one will even appear) without purchasing the ticket.

If it matters, I'm looking at the 1:40 pm flight from CTU to PVG on 4/29.