These Jims-USA #1091 tappet blocks are designed for racing applications, without pushrod tube cover counter bores and oil holes. Use with the Drag-race rocker arm shafts (ZPN233384) that have a grease hole. This complete kit includes a front and rear block. Has Evolution tappet angles and tappet bore size for use with Evolution cams. Please note, blocks are not polished, but come in a machined finish. Will fit Evolution Big Twin models from 1984 thru 1999.