outer diameter of heater duct and flapper duct
 

anybody know? i'm away from the car at work and can't find this info online and pelican doesn't list the diameter on the parts. i was going to pick up some hose/ducts on the way home.

looking for out diameter of left side standard duct on sc (one the goes to the blower motor, not the left side backdate duct) and the flapper duct OD.

part numbers are
hot air socket 930 106 326 01
heater control box 911 211 013 00

I used the common orange silicone high temp 2-1/2 in. ducting for brake cooling on my IROC front bumper install. Coincidentally the 911's heater system flapper box hose at the back of the car (that connect to the exhaust heat exchangers) is the same size. I used some leftover hose pieces from my brake cooling project to put new hoses on the heat exchangers on my '87 Carrera

I believe they are 55mm and 60mm tubes

measured them. left side hot air socket (standard) on 1978 sc is 75mm and flapper box duct is 60mm. thanks.