Tech Tip: If you have a 1965-1966 Mustang with an original 160 tooth flexplate/flywheel the 157 tooth can be used as a replacement as long as you have a 10.5 in bolt circle and are using the “small” bellhousing. The small bellhousing is typically aluminum, the larger 164 tooth is typically cast iron. The 164 tooth flexplate/flywheel can NOT be used as replacement for the 160.