On the '94 'W' s10 blazer there's a vacuum double T (two T connectors) back to the left (passanger side) of the distributor. Should this unit be plugged into the port on the plenum somehow or not? I have a nasty vacuum leak back there somewhere (whistling like crazy) and I can't seem to find any loose hoses back there.

 

www.autozone.com has great vacuum diagrams. All you got to do is sign up for their garage. Here I got this picture off their site for you.

 

Yeah I found that too but didn't quite match up with what I have on mine for some reason. I figured out the connections and plugged off the second T of the adapter that was empty.

She lives now, runs & drives without a whistle anymore :P