Fits Ford small block 289, 302, 351 CID engines that are internally balanced and are using a C4 automatic transmission. Has a 10-1/2 in. bolt circle and a 157 tooth ring gear. This flexplate does not come with an SFI certification. B&M's new Radial Tension Technology puts a new spin on flexplate technology. As engine performance levels increase, stronger flexplates become necessary. Until this point, stronger flexplates meant thicker flexplates. This works, but it adds unwanted weight and prohibited the flexplates from working as it was designed. Flexplates are designed to provide a protection against converter and transmission run out or OEM misalignment, which will cause transmission and/or converter failure. A rigid flexplate gives no protection. The ultimate design for a flexplate is extreme strength, flexibility and minimal weight. B&M's new RTT performance flexplate accomplishes this goal. B&M's design allows for the removal of unnecessary material from non-critical stress areas. Less material means less weight giving you the benefits of a lightweight, flexible design with thicker material for maximum strength!