QUOTE(euro911 @ Nov 26 2013, 04:05 PM)
IIRC, the control valves for the original 6 were a little different - they had a hole in the top (side) cap. Other than that, they are the same size and work the same.
I just sold the last ones I had, but search the classifieds. Bruce Stone probably has some
The other tin ducting is totally different
I have the 914 type flappers.
Extra hole in the -6 vents more hot air when not in use.