You must have gotten the last Millennium cylinders available. No one has any in stock and they don't know when they will be available again.
Maybe I just managed to snag the last set of 6 Millennium cylinders from Dart Aircraft parts in Waco. Other sources I tried were: A.E.R.O., Inc. in Illinois, Aircraft Specialties Services Tulsa, and J & J Air Parts, Inc. in Pleasanton, Tex.
I was told that recently, the shops that used to weld cracked cylinders have stopped, citing cost effectiveness, and the difficulty of access in the small cylinders. Whatever the reason, there apparently is a sudden shortage of these cylinders. When I talked to Superior, they admitted they are 7 to 9 months behind with their production of these cylinders.
As to balance, the separately boxed pistons came inside the same box as the cylinder. There was a 2 letter "piston weight code" on the piston box - in my case "WJ." All six "WJ" pistons weighed in at 722 grams. I'm really looking forward to feeling this engine come back to life - hopefully next week.