Is there a writeup or an article on how the YMS bellcrank arrived at it's present design?
From what I've read and heard some of the F2D pilots inverted the bellcrank to put the pushrod inboard and help get it out of the oil slick.
It also helped with some shutoffs. A number of good pilots were running shutoffs that worked off the bellcrank moving from line pull and would trigger the fuel shutoff.
Then everyone discovered that a swing arm shutoff worked just fine, especially if you didn't get cut loose.