So I did some math and settled on an engine choice
 

I've been looking at engines to swap into the truck and the one that i was settled on was the 4.8L V8. I have since chosen for the engine to be the 5.3L V8 for the sole reason of Active Fuel Management. The 4.8L and 5.3L have essentially the same EPA ratings, but the AFM is only offered in the 5.3L and larger engines.

So I did some math and if this 5.3L came in my truck with a 4 speed automatic the EPA estimate would be about 18.7 MPG City.

Thats almost 2 MPG better than my 4.3L V6 and over 100 more horsepower (and sounds a lot better)

I plan on swapping in a 6 Speed manual and driving the way I've learned on here. From that, i could easily match my economy but plan on beating it.

Until the engine in it now goes, or i finished everything else i want to do with the truck, i'll just be saving and aiming for better numbers with what i have now

It would be cheaper and faster and easier to sell your current truck with its large motor and buy the one with the best fuel mileage from the factory. Such as one with the four cylinder in it, then ecomod it, then get 30+ mpg instead of 20 mpg and enjoy 50% fuel cost savings at the pump. That is a huge ecomod

A 5.3L with AFM on a 6-speed will turn some pretty good fuel economy numbers for a truck.

My long time friend has a 4 cylinder 2.7L toyota truck with a 5-speed. He has 170hp and gets 22 to 24 mpg highway.
Its good until he trys to tow something.
Loading the bed of his truck with fire wood and putting my 4x8 heavy duty utilty trailer loaded with wood behind his truck turns it into a turd.

His toyota is the best all around small truck I have ever seen. It just does bad towing, on and off road its great.

It's okay to be slow when hauling at max capacity. Look at the loaded big rigs that just can't accelerate like you can even loaded, you can still be safe doing this.

If you are hauling 75% of the time then maybe you have a point, but for the occasional load it's okay to slow down.

My 4 cylinder 112hp Ranger fully (over) loaded with drain rock and a loaded trailer weighs in at about a combined 5700lbs. Geez it is slow. I haul this home from the quarry 11 miles about 8-10 times a year as well as a few (over) loaded firewood and misc runs. It's fun to really rap the truck out occasionally, it's almost the thrill of being back on the racetrack again, and I dare say it's good for the truck to get a good hard run. 161,000 miles and no sign of wearing out or slowing down from it's brand new lethargic state. The good maintenace practice is really paying off.

The rest of the time I'm getting about 29 mpg.

Have you considered the superior Diesel choice ?

You could probably match and exceed the V8's wimpy torque output with a 4-6cyl Diesel very easily - there is a reason those big trucks have compression ignition engines.