Btw, when you parallel batts, only the capacity increaes, not the C rating, so you will infact have 4s 20c 8000mah. Still plnety of power though as that means a total of ~160amps discharge rating.
KershawDesigns has the Firehammer MT body for a good price, along with the XTM Mammoth thats even better value:
http://204.186.93.64/Bodies.htm
I have the Mammoth body for my 18" WB TXT-1 project truck- perfect fit pretty much, and looks quite nice, based on the F-350 I believe.