RIVER: Midbulk transport, standard radion-accelerator core, classcode 03-K64, "Firefly".
The '03 Firefly Model was the last version of the Firefly design to make it to production. It featured a number of improvements over the earlier models (such as the Firefly Model One), notably the extenders on the 'wings' of the ship to separate the rotating VTOL-style ion jets further from the main body of the craft (which both keep the ship from shaking as much and allowed for two shuttle bays to be built into the design). Also, the 03 version of the Firefly is notably longer, with an extended 'neck', longer body, and generally roomier interior. (It still uses the reliable Trace Compression Block engine, though -- there's no shoddy Gurtsler in a Firefly.)
Images of the Firefly called Serenity:
Cutaway view of the craft, with the general layout of the ship color-coded:
"[A] design flaw in the models they use for the show. There's a support strut under each engine that's visible from time to time on the show. The problem is that the strut is supposed to connect the side of the ship to the bottom of the engine - to pull it into the "landed" position. The same strut, if connected, prevents the engine from rotating! If you know about this flaw - and watch the shows very closely - you can see the CGI folks "cheat" where the brace attaches, and even cheat where it emerges from the side of the ship via forced perspectives." - Chris Doyle, http://www.reasonablyclever.com/lego/firefly/photos2.htm(approve sites)
"The original Firefly was designated 01-K64, for model 01 and the year she first flew (2464). The "K" in the type class is a pun; "kei" is a Japanese word for "firefly." " - page 121, Serenity Role Playing Game(approve sites), posted by Dalton Spence