Chris I'm probably not the right person to answer. I want my 235 to be as quiet as possible, so I go out of my way to keep things silent. I use single exhaust, a muffler originally designed for either an Oldsmobile or Cadillac, hydraulic lifters, all sort of stuff like that. And no fan on the water pump. Just electric fans. Those old fan blades are balanced about as well as a concrete mixer and can make horrible noise at any speed over 30. Also...and I mentioned this a few days ago...I make absolutely certain the front part of my cab does not touch the frame at the mounting points. These trucks can telegraph all manner of noise through the cab via the frame. I've even considered using nylon bolts and nuts. And...I have the muffler as far back toward the rear as possible. I'm even considering adding another one in the exhaust line somewhere.
