In a message dated 10/21/2006 8:08:25 A.M. Pacific Standard Time, skipl130 at yahoo.com writes: PAUL, HERE ARE THE DIMENSIONS OF THE PISTON. 5" DIAMETER, 8" TALL, 1 3/8 PIN, 3/8" RING (3). JOHN Paul, I believe the distance from the top of the piston to the center line of the wrist pin is also needed. Francis