I measured mine at 8 cubic feet (84 model). For your info in 2015 I converted my old system to a Nova Kool LT 201/210 unit (compressor, suspended under stern lazarette on starboard side) with the RT6 freezer box which I mounted horizontally on the ceiling of the icebox, aft of the icebox trap door. Works perfectly and doesn't draw too much amps when running (3.4 and running about 20 minutes per hour when temperature is in the mid 80's). If it works that well with 8 cubic feet, it should do the job with 6.6 if you have that and have the room for the freezer box. The real secret to a good set-up is insulation and I was lucky that mine had been done well by the previous owner. Good luck with your installation.