"Big axle standard mechanical tappet assembly for Sportster Evolution (1986-1990, .8425"" O.D. The standard style mechanical tappet assembly is an excellent choice for OE replacement when ued in Panhead and Ironhead Sportster and can be used with the OE style and thread size pushrod adjuster and lock nuts. They can also be used when converting from hydraulic to mechanical (solid) on Panhead 1953-later and all shovelheads."