I was just working on some of this yesterday. First thing I notice is that the vacuum distribution block coming out of the manifold has 2 outlets; my 69 Ram Air 428CJ C6 Auto has only one. Have tried to include pictures of the routing of my vacuum tubing-keep in mind I have a tilt away wheel. Not at all saying that mine is perfect or factory correct, just that it all works like it should.
Just throwing out my $.02. Two auto trans re-builders I know say the modulator should have it’s own vacuum connection to the intake. This assures the vacuum is not affected from other accessories (headlights, A/C, speed control).
I’m using this diagram as my basis for routing. Just trying to get an idea of lengths and routing. Doing a concours restoration so I’m trying to make it factory correct.