how to measure/determine K26 "size"?

[auditude at cox.net]

Hi List,

I know there are different housings to the turbos, like K26's.  I've heard of #6, #8, etc.  Are
these determinable from some sort of markings on the turbo?  Or, does the housing need to
be measured?  If so, what measurement is it?

I would like to be able to determine which of my K26's have the smallest housings, if they
are even different, which I understand is a good thing for a street type application.

Thanks,

Ken