All the heads we make have cast-in letters and codes under the valve cover. It is important to note that World is not affiliated with Dart or Roush although very early castings may have some of these markings. When calling customer service, first reference the markings on your head. A code such as "I-037 ” or "WOR-070B" determine the family of head. Ford iron heads have “Windsor” (200cc runner) or “J/R” (170cc runner) cast in place. The numbers stamped on the end pads of a head are the abbreviated World part number. If the spring and valve size/type is desired, you must first measure the diameter of your spring and then the World rep can provide more complete specs. We cannot determine the chamber size by any markings so that must be measured by the owner.