Bird, based solely on what I can see in the pic ... the large
chipper chute seems to come from the center diameter of the impeller housing. If this is indeed true, that's where the greatest vacuum will be generated.
Perhaps an insert could be fabricated (3/4 ply or flake board would do it) This insert would:
A. fit snuggly into the large
chipper chute, perhaps 1/3 of the way down into it (secured somehow of course)
and
B. would have a 6" inch diameter flange (perhaps 2 inches high) mounted flat and to the center of this insert, facing up outta the chute, for attaching a 6" flex tube to, usually with a muffler clamp.
Were that to work, the only thing remaining would be some sort of harnessing or bracket to mount/secure the 6" flex tube. Don't make the tube too short.
If ya want, I can make a drawing and post it if this hasn't been made clear.
Potential Problems: size of large
chipper shoot where it enters the impeller. If too small, it may clog. The diameter of my bluebird is the same as the hose, 6 in.
Direction of impeller rotation on the large chute size: it may be blowin instead of suckin ...
Finally, maybe the small chute could be omitted?
And depending on impeller rotation, you wouldn't have to plug anything I think. My unit has a small
chipper on it also!
Just a thought.
Doug