Not sure I have the correct door release lever, or oriented correctly, but works for my long legs.
With the wider part of the rest towards the front?
Interesting, but with my legs I had to have it towards the back to clear my knee and the steering wheel.
I also just looked through my factory supplemental manual for 1966 and the 1967 shop manual and they don't show an arm rest. The photos may be hold overs from the '66 model.
Heres a pic of a 67 I found on ebay. The 67 I'm working on didn't have them but I was going to put them on
Kind of interesting where mine has 4 holes across the top and bottom of the panel and this one only has 3. Late or hold over from 66?