I'm going to order a 2wd 3500 QC SB SRW very soon - maybe today. The last decision is whether to opt for the 4.10 gearing. 50 weeks out of the year, I will drive it daily back and forth to work. 2 or so weeks will be used towing a 10k lb 5er. My Ford PSD has 3.73 and it works just fine. I assume the Cummins with 3.73 would be better. The Cummins with 4.10 would be better yet. But how much better?

How much difference really would there be in the mileage?

Does anyone know how much effect larger tires have on the final drive ratio? That is, how big of a tire would it take to make a 4.10 end up effectively equivalent to a 3.73?

Thanks,
Neil

 

Neil,
I think you will find volumes on this subject on this forum. Hit the search button and snoop around. Sounds to me like you would be fine, or should I say better, with a 3.73. Mileage does not change much between the two unless you are really flying. And, towing, it may be a little better with 4.10 with the heavier trailers.
Bob

 

You gotta go with what you do 95% of your life. In your situation I think 3.73 would work fine. Anything to help eveyday fuel mileage.......

 

Given your trailer weight, even if you towed full time, the 3.73 will do just fine. 4.10s really only benefit the heavy haulers.

Casey

 

I have had both and would get the 3.73 there is about 200 RPM differance @ 70 with the speeds on the highways today 75 in AZ the 3.73 ratio was just about perfect @ 70 with the cruse on I was getting 19.5 mpg The 4:10's only if you are heavy most of the time but your not .... I wouldn't even think of the 4:10 anymore .. but that's just me

PS I'm hoping the 3:73 are fixed by now!

 

Go for the 3.73 unless you really think you will up the weight of what you are towing. You will gain about 2k lbs of towing ability if you go with the 4.1

 

You can plug in any size tire you are thinking of running into this calculator And it will give you RPM's at the speed you like to cruise. Keep the Cummins under 2000 for mileage and above 1800 for pulling power.

 

I'd go with the 3.73 too...I like mine and have no complaints. Ocassionally pull pop-up trailer and can't even tell it's back there...
REgarding 3.73 fix, crawl underneath the truck with a 3/8" ratchet and check the level. If the dealer didn't check it at PREP time, I bet it'll be a quart low. Owners manual states 11.5 rear end (3.73) axle should be filled within 1/4" of the fill hole...

 

everybody is right 3.73 s are the better way to go i have had both and i currently have the 4.10s . besides you can always bom it later ( add a power box)

 

I have the 3.73's and keep looking for 7th gear on the highways as it is... unless your requirements clearly indicate the need for the 4.11 (and they certainly don't seem to) then go with the 3.73's...

 

For the experts....

My truck just went D Status which means I can still make changes, once D1 status hits that option is gone.

3.73 seems to be the gear of choice in this thread, especially for those of us who don't tow large, heavy trailers.

I ordered 3.73's with the 48RE and am going to 285 tires when the truck comes in. I want to go with 315's but being able to get it in the garage is a higher priority.

So....will I be OK with the 285's, 3.73's and auto tranny?

It would stand to reason that the 325/600, which makes it's peak torque at a very low rpm would have no problem giving me the OOOMMMPPPPHHHH I like at low speed.

 

Thats what I have and I think its a great compromise, still at freeway speeds I think it could be taller by using 315's but I tow 6000 in the mountains and have a motorcycle to load in the back so I am concerned about height and a little extra umph on steep terrain with the travel trailer.

Mine is the puny 460 so your 600 should do great!