You can use the Slash 4x4 body mounts and mount any body, but the only one I have seen with the proper dimensions is a Toyota Celica and it is $80 from Delta Plastics. Celica Rally Body The new Tekno SCT 2.0 is a beast.
I have a XV02, XV-01, TT-02, and TT-01, (along with 2 Traxxas 4tec 2.0's and an HPI Sport 3) all setup as rally cars. If you want to stick with Tamiya then the XV-02 is the best. Once you get a body of your choice it does cost more, but it doesn't need any hop-ups, it already comes with...