Thanks all for your responses.......
Just traded in my Gas vehicle for a diesel and sure surprised at increase in "cost difference" for diesel.... WOW! It seems to have jumped in price from 13% higher to 20% percent higher.
When Gas was around $3.19, I remember Diesel at $3.67, or 13% higher.....
Today Gas around $3.299, Diesel is $4.16 or 21% higher in a month or two.....
With my Gas unit, a Hemi 5.7L, my milage was 9.5 MPG pulling small (less than 4K Lbs. Drag not weight being issue) Trailer.
Hoping to increase mileage more than 21% and pull with a bigger safety margin using Cummings engine.
But...., looking to move up to small Fifth Wheel. (This RVing (travel) thing is getting under my skin.... give me more!) If I move up, additional drag, and weight will bring down that advantage real soon.