Campy "Z" Bottom Bracket
 

I got a used Record BB from e-bay to replace my ever-so-slightly slightly pitted one. The current spindle reads 68-SS-120. The the new one reads the same, but there is also what looks to be a 7 but I presume is a slightly worn "Z" just below the other information. They are both 112 mm. Is there any significant difference? I'm not sure what the Z stands for.