I was considering doing a 3.55 swap because my truck has 4.10's and I really don't have anything heavy to tow, just pickup loads. So my question is; is it worth my time and effort to switch over to 3.55's? And I know that the D60 is a much more stout axle but for my needs is it worth the extra money?

 

Being 4x4 id say its not really worth it, youll have to sit down and figure out how long it will take for the gear swap to pay for itself... im betting its a while. The D60 is a better axle imo, but unless youre offroading, or your TTB is shot and wearing the tires you dont need one. If you are set on changing gears, the cheapest option will most likely be finding a parts truck and swapping the axles.

 

Yeah that's the way I'd be doing it. Just trying to figure out if it would be worth it.

 

If you plan to keep the truck "forever" then id wait for a deal and go for it. bigger tires is another way, i got a steal on some SD axles but the rear has a brand new 4.11 r&p in it and is spendy to re-re-gear, but for $40 i can regear the front with my current front... so im sticking with 4.10s even though id rather have 3.55 or 3.73s. To compensate some i decided ill run 285s or 315s. That and swapping to the E40D is going to put me very near where i would be with zf 3.55 and stock tires.

 

Maybe I don't quite understand how this works, but how would switching to bigger tires compensate? I am running E4OD/4.10's/on 265's. Should I be getting a little bit better mileage than 13?

Also side note, is ~1900 rpm what i should be seeing at 60mph on my setup?

 

A larger diameter tire won't improve MPG calculated using the odometer. But your ACTUAL distance will be greater than what accumulates on the odo, so you multiply your MPG by the ratio of your actual tire diameter vs. the stock 235/85R16. Keep in mind that tire diameter is a function of width AND profile. For example, a 265/75R16 is actually SMALLER (but by something ridiculously small, something like 0.3%) than the stock 235/85R16.

 

running bigger tires hurts economy.your raising the vehicle up which causes more airflow under the truck.generally they're wider as well which causes more drag.to get them to turn,takes more energy because they're heavier.
out on just pure hwy,driving 65mph.it might just be a trade off but i wouldn't bank on getting my price difference back in the cost of the larger tires.
swapping from 4.10 to 3.55's should be good for all around 1.5-2mpg i should think all easy.especially at 55-75 mph speeds of course.
you want 'em sitting low with skinny light tires for economy.

 

So is the consensus that it is not worth to get some 3.55 axles for the mpg?

Also I had read another thread about whether somebody's T-Case was locked in or not. Would you say that 1900-2000rpm @ 60mph is what my setup is supposed to be at?

 

255/85/16 would be a good size to run. I dont think i beleive in the wives tale that bigger tires hurt mileage. I mean i assume they do, more rolling resistance, and wider tires mean more drag, but going from stock height and 31" ATs to lifted and 33"MTs i gained mpg, then i gained again when i went to 35" MTs I think the extra drag / resistance is a fraction of a fraction of what you gain from the extra ratio.

Yea id say youre speedo is pretty close, im around 2300-2400 @ 70 with ZF 4.11s and 235s 3.55s would drop you about 300rpms at cruise. Im aiming for 2k @ 70

 

Also my speedo is running fast by about 5mph. Is this normal with my tire size being 285/75R16?

 

So a guy off of CL has a front and rear Dana 50 3.54 gears Sterling 10.25 off of a 93 F250. Still waiting on the axle code. Would this be a viable swap for my truck? He said something about the front not being a straight axle. Does this matter? Also the front doesn't have hubs or brakes. Will mine swap over?

 

No, your front end is different.

 

Dana 60's and 50 ttb use the same wheel bearings, seals.. & brakes that's it

 

Ok so this swap wouldn't work for me?

 

If it were me, just keep the 60.. or you can sell the 60 for a pretty penny ( usually around $800-1100 ). Regear a 60 is cake compared to a TTB

Edit... is this a solid dana 50 or ttb?