Channeled 3 inches (height of frame), chopped 4 inches. Channel is easy on this, because of how the original floor was built. To channel we actually only had to cut 2 pieces out from the firewall back, 3 tall by 8 inches long, where the firewall tapers narrower than the frame. Interior floor is flat besides the kick up for the rear. Also had to slot the body for the rear axle.