Thanks for all the meaningful replies, with the work I do, which is rental equipment, I tow fairly often with my F150, mostly in the 6-7,000 range. I didn't quite foresee just how much I would be towing with it. You know what they say, hindsight is 20/20. If I had known now before I bought my F150, I would have jumped up to an F250, possibly with a diesel so I could have the exhaust brake for the big hills we have here in PA.

Oh well, I'll lose my hide if I sell my F150 to get a F250, so I'll make this F150 work!

 

You might be surprised how much your used F150 will fetch right now. The bigger issue would be finding an F250 that's not waiting in a lot for chips.

 

Have you tried locking out some of gears while driving? I think 8, 9 and 10 are overdrive gears. Try locking them out to see if that helps with daily driving and while towing.

 

my truck has the 6 speed, and yes, I regularly lock out gears 6 and 5 so it doesn’t t keep up shifting when going up hills or about to approach an hill.

And even doing that still will not solve the fact that it does not have the appropriate gearing, 3.31’s are wholly inadequate in my opinion, all for .1 or .2 of a mile per gallons increase.

 

When re-gearing, one thing I have learned. Go big or go home!. In other words, make a big enough change to do some real difference.
Going from 3.31’s to 3.73’s in your situation is probably not going to make enough difference to justify the cost. Go to 4.10 or possibly even 4.30 and then you will start to see the difference. I know there are those who will argue about that, but so be it.
Best of luck in your endeavor.