Poll not fair . Two C-Dorys one plug mounts from inside16 and the 14 screws in from outside, I can only cast one vote. Ohh well I would cancell out if I cast two anyhow. I would still prefer inside mounting as my arms are not long enough to reach the plug from the outside and with even a very slight chance of haveing a stick or whatever pulling it loose I want it where I can reach it. On the 14 the plug is a pipe plug, brass with threads which screws in with a wrench so it will not back itself out no matter what it hits.