here goes then.
54 = blue
55 = orange
56 = red
57 = black
60 = natural
Now if you have a 555 piston all 3 holes are drilled to an orange piston size (55), but if you have a 556 then you have 2 holes drilled to orange (55) and 1 hole to red (56).
It's really only the last number you need to use from a standard piston to get your various piston combinations.
hope that makes sense.
PS Carl how is putting up a link to stuff you have for sale going to help with his question
