Has anyone upgraded to 4.30 gears on a 2003+?

[WiscoProud]

I was driving home yesterday and started debating upgrades for my truck (very typical pastime), and was debating the benefit of upgrading the gears. Most cases I read about here people increasing the gear ration on 98-2002 4 speed cruisers after going to larger tires. The norm seems to be increasing the stock 4.30 to 4.56 or 4.88. However, since the 2003+ have a 5sp with a lower 1st gear, my axles have 4.10 gear ratios. Would increasing this to 4.30 make a significant difference? Has anyone done this? What was the impact to MPG?

The main reason I'm asking is when I changed my diff fluid (likely first time it's ever been done) there was more metal than I expected attached to the plug, including what looked like pieces of bearing or something. I wish I had taken a picture honestly, but I was oily, and didn't want to mess with my phone. My truck has 138k on it and isn't making any kind of noise or anything, it just got me thinking.

 

[OverLand Cruisers]

Seems like a lot of work to replace the R&P for such a minimal gain. Coming from a guy who switched our 80 from 4.10 to 4.56...
I'm thinking about re-gearing our '04 as it is gaining about 1K pounds of weight soon. I was thinking 4.88s may help motivate it (295/75-16s), currently not an issue with OE gears though.

 

[OregonLC]

If I built an 03+ I'd likely gear it. Once you're in doing lockers the marginal cost for throwing gears in isn't that much. And the locker/Nitro gear combo adds strength to the front end reducing the odds of breakage. 4.30s though might not be enough with 35s. I went with 4.88s on my 2000 and wish I would have gone 5.29.

For the A750 you'd have to do the math on the ratios to see what it would net out. 1st gear really isn't the primary consideration (there's low range for that). The issue is getting to the sweet spot in the power band in the 45-60 mph range when climbing a grade. With 35s and 4.88s on an A343 rig 2nd is too short and 3rd is too tall. Having an extra cog in the middle might be all she needs, but again you'd have to map out the math to make sure you can stay in the 3000-4000 rpm range at your desired speed.

 

[WiscoProud]

One point of consideration is that due to my location, I am not a rock crawler. I would love to try it, but my off roading largely involves forest trails and mud. I have considered 35s as well, but it seems like a lot of effort for not much benefit. Although if I could find something around 34", that might be nice.

Not to mention, this is still my DD and road trip vehicle, so it will still see a lot of highway travel. Due to it being my DD I do need to consider 1st gear, as I'm not going to be using low around town. I'll have to run the numbers to see what they would work out too RPM wise.

 

[OverLand Cruisers]

My '04 with 34s (295s) is great to drive on and off-road. Even at high elevation it has tons of power and effortlessly maintains 75+ even on grades.
Right now it only has a Slee belly pan and sliders. However the eventual build calls for a Maggiolina (130lbs.), ARB with Warn (200 lbs), Slee rear bumper with dual swingout (250?), 2nd spare (85?), 2nd battery (80?), large drawer system with an ARB 63 quart fridge (300?), at times 20 gallons of H20 (160ish) and 15 gallons of fuel (100ish). Spare parts, passengers, and dogs not included that looks like it will be gaining over 1300 pounds...wow! WTFO...maybe I need to re-think this...
I'll definitely be swapping the 860s for 868s.