As an option, customers can order Probe's 4340 H-beam with ARP bolts (far right). The I-beam type (left) is a more basic type, and the machined I-beam (center) is somewhat lighter, and comes standard with the 427 Cobra Classic package. In stroking the displacement to nearly 427 cubes, the rods slightly lengthened in order to clear the crankshaft counterweights.