I have an '05 2500 with a Cummins. The AC is not what it used to be, so on the way home today I stopped at the auto parts store and bought a recharge kit. Here's what I need help with.....is the "Low side" next to the radiator or on top of the canister near the firewall?

 

Well, I now know that the "Low side" is not next to the radiator. The gauge will not fit on it.

 

Low side port is usually closer to the firewall.
Sorry I don't know exact location. Often it has a black cap on it