The smooth shifts are the result of the elimination of any leaks at the 3-2 valves on the top of the valve cover. Any leakage up there will drop the vacuum to the VCV slightly and might have resulted in reduced transmission modulator vacuum depending on the original vacuum level to the VCV. In my specific case, the vacuum to the VCV was 12". So, any leaks at the 3-2 valves would not have reduced the vacuum below 12" therefore any leaks at the 3-2 valves would not have been noticeable.

The second line that is connected to the VCV (not the modulator......it's on the side of the transmission........at the very end of the hard vacuum line from under the hood) is the vent. It's connected to the side of the VCV and it goes into the cabin. This provides a source of "clean" air for the VCV and it is less likely to be taking on soot from under the hood. You probably should reconnect it..........you won't affect the performance of the vehicle at all.

Now, you may not like the SD the way that it is..........the shifts may be too "soft". I didn't like mine and decided to firm them up a bit. If that's the case, you need a Mityvac. Just repost on this thread and I'll show you how to adjust the vacuum from the VCV to the modulator using the Mityvac.