I think someone on here said if you regear to 3.42 from 3.73 (stick or auto?) you should pick up MPG. Anyone know for sure? Is it worth the cost?

 

I believe cost is about $1200 if you replace both ring and pinions as well as the rear end bearings,seals, rear end oil, etc. Labor is probably $500 to $700 which would cover both.

About a 1.5 to 2.5MPG increase. I thought about it and instead I went with the 285 / 75 / 17 dura grappler tires which helped my mpg. They are the skinest tires in the 285 series - I know that does not make much sence since 285 is the width but they are significantly narrower than 285 BFGs.

Search 3:42 and you will find LOTS of info

 

I wouldn't do it. It would take at least 5 plus years to just break even, and depending on how many miles you drive. Just maintain your truck and drive it economically.