Can somebody please tell me what size T fitting to use?

 

does anyone know where to get a t fitting ? the autometer one is crap ... i need the size as well as the size of the hose so i can replace that as well

 

Hey I'm having some trouble and i figured everyone in the thread may be able to help me.
So i put my mechanical boost gauge in my car and ran the vacuum line right where someone else put it in.
But problem is my gauge reads about 20 vacuum just like Joe Schulte car does. I want mine to read the boost it is providing i have a supercharged cobalt so it would be best if it worked correctly is there something I'm missing or that i can do to make this work?
Thanks!

 

Which wires need to be used in order to make the gauge dim with the rest of the dash lights?