[Rory McNeil]

Since the OD of a 157 tooth flexplate is about 1" smaller than a 164 tooth, you will also need a block plate for a 157 tooth flexplate as well. On a Ford, the thin steel block plate is sandwiched between the back of the block, and the flexplate, and is needed to properly locate the starter in relationship to the flexplates ring gear teeth.If you were to accidentally use a block plate for a 164 tooth flexplate, the starter would be too far away to allow the teeth to engage.