looking to buy an ecodiesel

My current vehicle is a 2007 Tundra dc longbed that has been a dam n good truck.

It has 320,000 miles on it and just began to have a transmission issue. Since it needs tires and brakes, I may as well buy a new truck and sell the Tundy as is.

Im a pool guy and drive approx 40k miles per year. I also tow a boat and rock crawler from time to time. Both less than 10k lbs.

Since my Tundy is also a half ton truck i imagine the towing characteristics will be about the same.

Would you agree?

Maybe better off the line towing since the dodge is diesel?

I'm in it for the mileage since it's a 100% work truck.

Also, diesel is $.40 less per gallon in southern California.

I'll get a Cummings dually in a couple years to tow(only) future planned heavier purchases.

Thoughts?

Thanks