If I'm not mistaken the Pro 1 is 7" wide and 12" high , the Predator is 7" high and 12" high ( I think , or a touch taller ) and the Bullseye is 6 3/8" wide and 12" high . Chassis lengths vary from manufacturer to manufacturer . Are you planning on building your own chassis ? If so, with the stockcar chassis you built I'm sure you'll come up with a design you'll like