I'm pretty sure it's going the unibody way- the same as the new Tundra. Original thoughts were that it would be on the same frame, which is unfortunate, as I was a big fan of the smaller trucks. My 04, is visibly smaller than the later models.
With the TNGA-F (global architecture) of the trucks and SUVs, the Hilux, Tacoma 4Runner and Prado are going to have basically the same frames, which are smaller versions of the 300, Tundra, LX600, and Sequoia. Toyota did this for a multitude of reasons, but the benefit will be their higher end frames going on all of their true 4x4s. Toyota can also "easily" use any TNGA-F plant to made other TNGA-vehicles if needed to increase supply as needed. Should save Toyota a lot of $$$.
