Fixed my Suburban propane heater. It had a terribly loud vibrating noise when it heated up. The entire rear section of the bottom bunk had to be disassembled to have enough room to pull out the heater.
After that the heater is removed from the metal case.
I determined the fan was making contact with the shroud due to a stripped sheet metal screw where the assembly is connected to the rear intake/burner housing and the fan not being centered in the shroud.
Looks like poor factory assembly to me. Replaced the screw with a larger one and adjusted a couple pieces of sheet metal which fixed the problem.