another point to remember is that the 16 came before the 18, 21 and 28 and contrary to popular belief is the DADDY of the nsr family. look at the spencer rep on this site, which clearly states what i am saying (Top of the table, okay not quite standard but who would know? he that does know will be too busy standing at train platforms numbering the frieght wagons, while mr smooth is stepping in on their lady with an mc16 running classic.) by those in the know.