Your coach needs a 120/240V 50A circuit. The NEMA 14-50R receptacle is 3-pole, 4-wire, and grounded, as described above, and looks like the picture. It is rated 125/250V, and is exactly what is used for most electric ranges.
If the existing receptacle has two parallel slots and a round hole, it is 240V only (NEMA 6-50, assuming itís 240V). Do NOT attempt to plug into that, though your shore power cord wonít fit. Call a sparky if itís wrong. There are also obsolete range receptacles that are 3-pole, 3-wire, ungrounded style, which while being 120/240V, is also NOT what you need or want. Again, call a sparky.
Tom & Jeri
2018 Coachmen Galleria 24T Li3