Although I have no first hand knowledge of your Pulse, an online search for a Pulse Owner's Manual (OM) does show this statement contained in the OM:
Generator Fuel Supply
Fuel for the gasoline or diesel generator is taken from the main fuel tank through a special feeder tube which is higher in the tank than the feeder tube to the motor home engine. This arrangement prevents the generator from running the motor home fuel tank dry.
Propane Generator (If Equipped)
Fuel is provided from a dedicated Propane tank.
That would suggest to me that the propane generator was offered as a purchase option and if installed, the fuel source is a dedicated propane tank.
It doesn't appear that the fuel source is one (diesel) or the other (propane) and not owner preference.
"I would rather have questions that can't be answered than answers that can't be questioned."
2018 Anthem 42DEQ