After 4 on the road repairs of the engine preheat hose we took our coach into Elite RV repair in Harrisburg, Oregon. They originally thought they had to run two new 30 foot heater hoses but discovered that Monaco had used a product call tuff pex along the frame rails and only had to replace 2 three foot sections of hose with a silicone heater hose. Not sure this problem will impact anyone but might help someone in the future.