went down into the old downtown department store sub basement today. managd to find the main junction box for their old Lamson system. most of the brass lines are cut but one still goes up to the third floor. i tried using my coleman leaf blower to clear it out. shot a bunch of ancient reciepts and some weird crusty grease all over my jacket. does anyone know if the 4 inch carriers from the old postal systems will fit these retail lines. my hands are covered in soot. reply soon.