Rear gear change

I can only tell ya this .. I was running 402's with 3:70s .. I 'am in the process right now of changing .. Myself I bought a cut off just for the rear ends .. I found low mile cut off that are Eaton 404s & 3:36's I really wanted to go disk brakes but couldn't find what I wanted seems most of those with disk brakes were geared to high for my set up..
It's some work but it was the most efficient way for me to achive my goal since my suspension was in good shape

 

Cost is going to depend on what make and model of axle you have. If you’re lucky you can change nothing more than ring and pinion and seals in a partial rebuild of your existing rears but again need more information on what you actually have to determine this.

 

Those 336s will be nice after the 370s,

Gotta say i didnt much care for 24tall rubber on the 3.36 and 13 speed, felt like getting going from a stop was almost impossible without using low low when heavy and loaded. But 22 talls (24 short) hit the spot very nicely

 

Thanks thats good to know ..My wheels were buds on 24:5 tall rubber I wanted to update to hub pilot I haven't bought wheels yet cause I'am on the fence about running 22 talls or staying with the 24:5 which are getting harder & hander to find but I like the little bit extra they offer on the upper end speeds
I run a 15 speed so loaded I always started out running a couple gears in the basement

 

I went the opposite way back in 2007.
3.55 and switched to 4.11 as I was going from dry van to super B train 140,000 lbs in the mountains.
I had full lockers. It was slightly cheaper at the time to change out the crown and pinion gears. Cost me $5,000 back then.
Problem is the mechanics didn’t quite get the gear lash correct and four years later the front diff came apart.
Best way is to just change out the whole pumpkins, then the gear lash is set from factory. Much less labour cost too.

 

I went 3.70 to 3.55 - 13 sp Set S60 - loaded 80k or less,

It's OK, as 50% of my miles are deadhead, but I did lose some pulling power.

I had my pumpkins turned in to a local shop and rebuilt - it was time anyway - $4k or so a couple years back.

 

On a 15, probably not as big an issue, but id still say price 22 talls vs 24 shorts, theyre the same but 24 shorts will be marginally better on fuel.

 

What makes the difference in fuel?

 

Sidewall flex iirc, theres simply less sidewall in a short 24.5 than there is a tall 22.5, less sidewall = less rubber to flex

The overall outer diameter is virtually the same

Note i said marginally