Clone

I bought a new travel trailer that isnt going to put me over my tow rating or my gvwr ratings, but it will be much closer than I currently am. Truck has a tow package with the 3.55 rear end. Would there be any benefit to upgrading to a 3.73? Would this improve payload at all, or would I be better possibly getting some air bags? I figure the 3.73 would help the truck get moving better, but does it provide any other benefits? Truck is a lariat screw. Thanks for any input.

dont slow down

I don't think changing gears will increase your payload. Gear changes are also very expensive. If you are just looking for a little more power while towing I would suggest looking into a tuner with a towing tune. I'm assuming you have the 10 speed transmission too?

RLXXI

Tuner yes, 10 speed no, not in 2013. 6R80.

Op a custom tow tune will definitely make a huge difference.
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River1

3.55 is Fords sweet spot gearing between mileage and power. 3.73 will be a noticeable improvement but I'd consider going higher if you're going to do a lot of driving in the mountains. Also, a Ford engineer once told me that the chassis can tow or handle more weight than the GVWR or\and towing limit. It's the suspension that limits the ratings. That's not true for all manufacturers. Anyway, bags wouldn't hurt. He also said what a lot of people don't take in to account is as tire diameter goes up, tow rating goes down with the RPM's. It's common for people to put bigger tires on their trucks which changes the engines tow rating. A reason not to tow in overdrive. Chassis, suspension and engine\drivetrain tow ratings are all factors of GVWR.

River1

Gears definitely effect tow ratings. Should be plenty of charts on the innerweb showing this.

Edit: Should have wrote effect tow payloads instead of ratings. My bad.

Clone

Thanks for the input. I may look into the bags and see how things go. I do have the 20" factory rims, and I know I am not going to be winning any drag races, was just looking at ideas to make things easier, and the suspension makes sense. I wondered if the frame could handle more, but made sure I wasnt buying something that put me over the gross combined, but I am sure I will notice the added weight. Trailer is about 1700 lbs heavier than my last.

River1

If you look up what gears were available on your truck as built you should be fine with any of them.

RLXXI

Cheapest and easiest route is a custom tune. My truck has 3.31 and pulling a 16' ski boat was a drag, literally. Felt like I was pulling with the anchor deployed. Tune and now I don't even notice it back there.

If 4x4 and you regear you have to do both axles, cost parts/labor will run you around $2,200 depending on location. $400 will get you the power you want. I highly recommend MPT or 5*. I have both and am very satisfied with performance. They both make tow specific tunes.
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13XLTEco

You will be limited to what you can tow without exceeding the payload rating. You cannot change the payload rating of your pickup. Payload rating is on the sticker with yellow on it that is stuck to your driver's side door jamb. Tongue weight is usually 10-15% of the camper GVWR. That takes away from the payload as does passengers, anything added to the truck since new, and cargo in the cab or bed.

River1

You're absolutely right about not changing the ratings. You can change the amount of a trucks payload with gearing but you're not going to change the payload rating unless the manufacturer lists different ratings for the different gearing.