If you have power valves, its definitely a cheetah. They make a 72, 73, and 74 bore i believe, they're may be more. You could take your head off and see what size pistons are in it. A 72 bore on a 4mil would be a 472, 73 i believe would be a 485 and so on and so forth. So be excited.... The cheetah cylinders do not have sleeves, they are nikasiled and last a lot longer than sleeves.