Let's say I have 3.54 (?) and want to go to 4.10. How much would I expect to pay for that? any other ways to get the + MPG effect I am looking for?

 

I bought genuine Dana/Spicer parts as a kit--ring, pinion, bearings, shims and seals. Think I paid right at or under 400 bucks locally. That was a cash exchange, not sure what the parts really cost. I did all the labor--it was my first r&p swap. There is a lot of heavy work involved with these bigger axles. Having worked at many shops, I'd guess you'd be out a solid 1500 bucks with parts and labor. If you found a place that specializes in gears, it may be cheaper 'cause that's what they do. A regular shop would lose their butt doing a r&p swap. You could prolly score a used rear for less than a grand if you shop around.

 

You will loose MPG going from 3.54 to 4.10, unless you are towing really really heavy in the mountains. And even then I don't think you'd gain any MPG.

 

I agree with apwatson, if you want to gain MPG then you would want lower gears say 3.07... but good luck finding them

Michael

 

I dont think that you would gain mileage even with lower gears. Depending on the tranny and tire size i think that 3.55's or 3.73 are right in the optimum gear range for most. Gears are most likely 250$ and bearings and a setup kit 150-200$ and the guy who did my stuff in my offroad truck charged 100$ to set them up. I would say if you swap gears stick with Spicer stuff, there are other good gear manufactuers, but there are also some crapy ones.

Ian-

 

I had about $900 in my when my rear end went out, that was an R&P, master install kit and a carrier rebuild since my carrier was what tore everything else up and that was just the rear differential. $1500 sounds about right to me for front and rear w/o needing carriers. As far as gears and mpg I have 4.10's which I did not like at all with stock tires out on the highway but after switching to 35" tires they are alot better, with the tires my ratio is about 3.73 now which is fine on the highway and my mileage went up with the bigger tires because I am not at the governor all the time, and it will be even better when I get a 3200 spring so I will have a little more top end speed if I want it.


Chris

 

My buddy from SD has a gen2 automatic with tallish gears. He has had really poor fuel mileage and performance pulling his fifth wheel. I believe that either one of the higher ratio gears would help him by putting his truck into the 2000 rpm towing sweet spot. Right now, he can't pull fast enough to get the rev's necessary. I don't think that pulling at low rpm's for a long period of time does anything any good. My old first gen out pulls his rig, runs cooler and gets way better fuel mileage.
I could use his gears for my truck but won't swap as mine are a bit rough. I am pretty sure you would be happy with lower gearing and your automatic would like it too.