The brass fittings are for the back of the gauge itself. The hose that came with the gauge will fit into it. There should be some of the fitting already threaded onto the back of the gauge. You can use this without any of the other supplied brass fittings for your install. Be carefull when you unscrew the brass nut on the back of the gauge, because there is a small brass "barrel" inside. Dont loose it. To install the hose to the gauge, you must remove the brass nut from the gauge, catch the small barrel, and then 1. slide the nut onto the hose and next 2. slide barrel onto the hose. 3. Thread the nut back onto the gauge. The nut and the barrel will make an airtight compression fit to the gauge. Once you get the gauge all mounted up, run the hose through the dash and out to the engine bay. Be carefull not to kink the hose. You will need an adaptor to fit to the factory nipple. I used an Elbow adaptor 1/8" X 5/32" that was perfect. There is a black cap on the factory nipple that you need to take off. Make sure you have plenty of hose and then trim it to the length you need it, and then simply use the adaptor to plug it all together to the factory nipple. Done!
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