Thanks for the reply's.
I have kept up with maintenance. The truck only has 57,000 miles.
I have 410 or 411 or whatever Ford gears Ford put in them in the low 400's.
I went with the V-10 over the diesel because I also had a Lance camper and needed every bit of weight capacity I could get in a 350, and I had been told that letting diesel engines sit for long periods of time w/o being driven was not OK. The truck sits sometimes for several weeks at a time.
I have let it go up to 4000 rpm at times but man it sounds awful when it does and mileage goes from bad to insane.
Thanks again,
John