i use the ext. chassis and love it, just consider which lipos you buy for fitment with the included battery hold down, or make a new one
most 1/10 electric truck bodies will fit fine,i believe the proline t4 body is a good fit, the stock crt.5 is a little short imo but it works
1/10 truck tires complete the package as the tires that come with it are a little small
i also run the med/blue springs... some run the heavy/white springs
i run the mm , 3s , 9L combo and its great geared 15/46 its plenty fast and powerfull , and temps are cool