Originally Posted by
Genghis the Engineer
It does surprise me that CAA allowed transfer of ex-military Bulldogs onto CofA without modification of that valve, but they did.
I guess it's because of the commonality with Pups, which were never required to change either, so the Bulldogs just got grandfathered in.
Although personally, I always use left/right. For the simple reason that if there is a suspected fuel problem, I can just switch to the other tank, rather than having to make a 50/50 choice.