The overall length of the arms is 18 1/2". The "pins" are 17 3/4" center to center.
This was a lever type operator, and the lever broke off. I am not sure I have the broken piece any more, and it is not something fixable in any case.
The next smaller lever in your catalog is a crank type of about 16" overall. A crank type probably would work out--no reason why it shouldn't.
