Worth the switch to 4.30s?

Coming from someone who has a V-10 X originally with 3.73`s I can tell you the 3.73`s will not be enough for a 9klb trailer! my trailer is 9200lbs loaded. I towed one season with 3.73`s and switched to 4.30`s for the next season.

You will notice how much better it tows. you will be much happier when you get to an incline and the X pulls right up. you will get about .5 mpg better towing. It will also stop hunting for gears because he engine and trans will not be working as hard. When I had 3.73's with my trailer I couldn't hold O/D at 65 because the RPM's were to low in O/D. And too high in 3rd. With the 3.73's it would stay in O/D with no issues. It's all about how efficient the powertrain is, and with 3.73's and a heavy trailer it will not be efficient with higher gears. The lower gears (numerically higher) will always tow better!

Add in a 5star tuner and it will pull with the diesel guys all day long! I would even say 4.56`s wouldn't be out of the question even with stock size tires!

Yes it is well worth it!

Gear box ratios are torque multipliers and generally are about 10% difference
between ratios offered

Your 3.73's multiply the drive shaft torque by 3.73...4.3's will multiply and
provide about 15% more torque

So if the drive shaft has 100 ft/lbs of torque, the 3.73's will send approx
(there will be losses) 373 ft/lbs to the axles. 4.3's will send approx 430 ft/lbs
to the axles

MTWR's is very dependent on axle ratios...just check any brochure or specification
sheet from any OEM

Absolutism this is NOT, as the axle ratio is just one of the components of this...meaning
to just talk about a 3.73 vs 4.3 is out of context of the whole
system. There are many other factors. Diesel, big block, small block,
forced fed, cam profile, etc, etc

The tranny gear ratio(s) and the ICE's torque curve must also be factored in...as
would the tire OD...best to use their rev's per mile...that is more accurate

"Torque band" is the HP/Torque curve and choosing the tranny gear ratio
and axle ratio vs whatever you wish as your priority

If MPG is high on the 'have to have' list, then the lower numeric diff
ratio.

If towing is high on the 'have to have' list, then the higher numeric
diff ratio.

BUT...you can't have the best of both worlds...there will be compromises...

Not worth the investment. You will not have any problems.

Why not try it before changing anything. Then you can decide. Its not like it won't pull it at all.