I've seen this comment a couple times in this thread and I have my doubts that it's true.
The biggest reason I say this is that, by the V.I.N., there is no way the insurance providers can TELL what tranny it is, but they can darned well tell if it has a 340, or other engine, by it.
Unless they ask on the phone (or in writing) and you're not intelligent enough to tell them it's 3 speed or auto, there's no way they can tell.