[Bob Moseley (RIP)]

And here is where the speaking tube finishes up inside the crew cab. Again it is presumed that the completed configuration is the same as that in the truck cab.

With regard to the goose neck featured in the first image, it appears this was a later modification that was used when some Blitzs were converted to fire trucks. A speaking tube connection was still required to communicate with personnel on the back of the truck but as one can imagine that would be in an open situation requiring a higher truck exit point.

Bob