Are there more than just the one stock racer body or do more appear throughout game play? I don't mean full cart like the egg one or tank but blank bodies like the first cart to start customizing with?
You can change the suspension of any kart by going into the Kart Parts page in the "My Karts" section of the Popit. If you want a blank body to work with, select the base "Paper Arrow" body and change its suspension. Once you unlock everything, the suspensions you can choose from are:
Dragster Hover Low Rider Monster Truck Stock Tank (with treads)
The shape of the body will change to match the suspension.