Late model RVs have a Hansen/Sturgis Model 250 Low Pressure Quick Disconnect LP Port which accepts a 1/4" MNPT Plug. Some older RVs had a Model 3/375 Low Pressure Quick Dissconnect Port. The Model 250 Port is a Low Pressure Port (5 psi Max). You will find Model 375 QDs where Grills connect to household Natural Gas sources. The Model 250 QD and Plug look very similar the the High Pressure Sturgis 5LP QD / Plug which is rated at 250 psi. The Model 250 (low pressure) Plug will mate with the 5LP(high pressure) QD but will not pass gas. The 5LP (high pressure) Plug will not physically mate with the Model 250 (low pressure) QD. This confuses a lot of people trying to plumb gas on a RV.
Most hardware stores carry the 5LP high pressure connectors / hoses. RV specific Model 250 or Model 3/375 QD hardware are somewhat harder to find. I found an excellent source for RV QDs and hoses here in Houston.
Jesus Martinez is very knowledgeable and offers overnight if needed.