The box came back as my safety to keep from accidentally putting a finger where it'll get hurt. Plain old cardboard box. I'd like to take credit, but it's my wife's idea. One flap is folded into it and the two pieces of cardboard make it thick enough that it wedges behind the lever with B and C on it. Yeah, I can push the box out of the way, but not the kind of brush against it that I might do by accident. I'm hoping that if I'm wrong someone searching the web for "SC4 threading" or "LMS3540 threading" comes along and tells me how to do it better. The graphite piston is cut slightly oversized, hollowed, drilled through and slightly oversized. Now comes the meticulous part of putting it on the push rod, trying to fit, taking it off the push rod, turning a little more and so on.