[Carl n Susan]

Believe what BB_TX wrote above. Earlier Montanas didn't have the Red Regulator on the opposite side of the Switching Regulator. Just a flex line to an iron pipe. You had to be very slow and careful opening that tank. I believe that changed around 2010 or so.

The Switching Regulator was traditionally located on the door side until somewhere around 2013/2014. Why it was moved to the off-door side is unknown. Having it on the door side made checking it as you left easy. It tends to be forgotten on the off-door side location.