70-71 340 would be a silenced breather. 68-69 is unsilenced. Just some info you may want to know. You can buy the 68-69 new pretty cheap. 70 -71 expect to pay $300-$500.
its always been in my part of the world, a"silenced" breather had the snorkels. unsilenced did not,regardless of size.maybe I mislearnt,anyway you know the one I seek apparently. thanks for the link too>