I have a 1965 Mustang Hi-po 289 . I was looking at a book on the HI-PO 289 and they said . The HI-PO rods used part # C30Z-6200-C and a C3AE-D casting number . Later Ford used the Boss 302 rod C9ZZ-6200-B As a service replacement for the 289 HI-PO . They shared the same center-to-center lenght of 5.155 and have a weght of 581-593 grams. And both use the 3/8 inch bolts .