wildroamer

I just changed from 3.31 to 3.73 in my 13 4X4. Really couldn't be happier. I bought Ford OEM gears form Tasca for a great price, bit of course you can do better with an aftermarket brand like Yukon, etc.
You'll need to order a master install kit too. Mine was a Yukon.

marshallr

It means your suspension can't handle more than 1385 lbs added weight to the truck. An 8000 lb trailer isn't going to be practical even with 4.11 gears. You'll have a tongue weight of over 1000 lbs leaving you only about 300-350 lbs for all passengers and gear inside the truck. Some trucks have a payload of 1800-2000 lbs.

If you pack light it is theoretically possible. You'd be slightly overloaded. But in reality you'd be better off with a lighter load or a heavier duty truck.

Magnetic157

I agree, with that small of a payload number towing 8,000 lbs isn't really the best idea. Even with an generally unrealistic ~10% hitch weight that would only leave you with around 500 lbs. If you have a more realistic tongue of 13% then you are down to 350 lbs - which is barely enough then for the driver and hitch. Once you minus out a 175lb driver, a 100lb hitch, any mods and some miscellaneous travel stuff you are maxed out - and that assumes no passengers.

If you are going to towing frequently enough to want new gears you should really be in the market for a lighter trailer or a truck better able to tow that kind of load.

If your payload sticker was above 16-1700 I'd say go for it - but 1,385 is a little low for that weight trailer IMO.

acdii

My 14 had a 1470# payload, and I figured 7600# was the limit. More like 6300# once I got it hooked and weighed with everything in it. By the time I was done, I had about 150# left after myself. This was with less than 11% TW too. My 16 has 1580# payload so without any changes to the trailer I should be OK in the weight department now. Would like at least 100# more Payload, and if I were to remove the power running boards, I may have just enough to take the whole family with instead of using a second car.