Interior Heater hose size?

[Bus'n it]

Curious to know if 1" ID heater hose is standard issue for the hoses running inside the bus? I found a 30' roll of silicone heater hose on Amazon for $160. I am thinking the new hose will go underfloor outside of the bus.

 

[cadillackid]

Yeppers 1 inch is common in all but the van cutaway busses

That silicone hose is nice !