Fare basis codes are alive and well on Southwest but are hidden from the user unless you're a travel agent. You can view them to your hearts content on Expertflyer, but you won't be able to do anything with them other than to go to Southwest.com and book the lowest fare in each of the three categories, wanna get away fares are an amalgamation of all the non-refundable fare buckets.

You can also see what class your booked into on your boarding pass.