Evoracer - you can use body post extensions to fit the GT style bodies where it goes in the back windows. You can get those from HPI. Its a hollow post that slips onto your existing body post and clips onto your body post with either a body clip or a small self tapping screw.

Here's one available from RC Mart that are aluminum. The HPI ones are plastic.
http://www.rctech.net/forum/rcmart-c...lable-now.html