Ford put a Bulletin out on the size,thickness and weight of Hipo balancer washer.The balancer,bolt,washer and cookie cutter all played part of balance along with flywheel and Hipo rods.If your just putting a motor together without balancing it good luck as we don't do my motors that way and never have.There is a difference on thickness and weight of washer from standard washer.That might be good discussion for someone else to start a thread away from the classifieds!