How many of us are there? Owners of Dodge based RV's?

Oh, yeah ... allow one or more shots of PB Blaster or Kroil to soak into the fittings before trying to remove them. Patience is much easier than having to replace brake lines due to damaging stubborn fittings.

On really old vehicles, with clearly corroded fittings, I often spend up to a week letting PH Blaster or Kroil soak in and unfreeze the connection. Usually, this involves one to three re-applications per day, with gentle rapping on the fitting to help the solvent soak in.