I don't have easy access to the A/C vacuum barb at the vacuum "T" back of the intake to put calipers on it, does anyone know what size it is? What size rubber hose fits on the barb?

Wanting to use it for the vacuum gauge on my dash.

I did a search, a lot of discussion, but no indication of size.

Thanks in advance.

 

6.70mm on the dial caliper is the OD of the Shaft on the smaller vacuum fitting on the back of the LS1/LS6 intake.

 

That looks as though it is for 6mm hose, rather than 1/4 inch hose. Doesn't appear large enough for 1/4", with the barb at .264. Anyone know?