TKautos- if you go 5.13s remember the pinion gear is tiny with fewer teeth to mate with the ring gear. Since you deal with ground that slips ( mud & sand ) there's less stress on those teeth. But if you ever go on rocks, be wary of tire spinning. When those tires spin fast then instantly grab traction, that's stress on the teeth.

 

So, 4.88's would most likely be optimal. I want the best possible fuel economy with the best possible performance.

 

Your in a situation. 5.13s will give you the power but you lose economy due to higher RPMs. And the pinion of a 5.13 on a Dana 30 is tiny with very few teeth in contact with the ring gear. That with your admitted heavy foot in an off road rock ledge attack is a recipe for missing teeth.

4.88s may not give you enough of the low end you seek in contrast to 5.13s, but will work at freeway speeds and have more teeth in contact between the ring and pinion. No matter what gears you go with, your foot is in charge of efficiency. Aerodynamic drag from frontal area and speed is the number one factor in fuel efficiency. Number 2 is rolling resistance from tires.

So if you do nothing but street, loose dirt, and prioritize speed above mpg then 5.13.
If you want dependability, 4.88 with more gear teeth meshing in a Dana 30 is better.

 

This info has really help me too. Thanks.

 

That makes sense. So it sounds like a choice to make, but definitely between the 4.88's and 5.13s. Thanks for all your help. If I may ask, is this out of personal experience or just common sense and what you have gathered thus far?

 

Combo of things: have been into cars for 30 years, friends were gear heads; I had a Shelby; years of thinking of changing gears myself, hundreds of pages of posts on this forum, common sense. I'm into well engineered design. I was planning on 4.88s myself, but I can live with 4.10s. I'm in the power band with 35"s - 2700~3000 rpms on the freeway any don't need to race at stop lights. If I were still into speed, I would not invest in this platform to race. I'd rather build the rig to be dependable out in the middle of nowhere.