Dear Roger: I was referring to part number 25...but a pressure check on either line might be a good idea as well. If you have a mightyvac hand pump you could check for pressure leakdown that way as well. Might be an easier way to go..as the gauge is built in and is pretty sensitive..If you buy the plastic one available at most autopart stores for about 30.00, the kit usually includes several adapters and some extra tubing. Hope this helps some.