i am looking to find the road series for the SP 48' containers i know many were in the 680000 series and apparently the went into the 690000 series seen here but where did they end? http://www.rrpicturearchives.net/showPicture.aspx?id=342797 also any idea why these numbers were chosen? were they to prevent any road numbers from alligning with rolling stock? i plan to get some 53' containers for my modern SP and need to know this. any help is appreciated thanks