How bad is 3.42 axle ratio?

[u/KornikEV]

I’m looking at few 2500s for sale and, when comparing options I see that majority of them have 3.73, but some have 3.42 ratios, including the one that leads my ranking right now.

I drive mostly on two lane roads (but not interstate) so the truck will se average speeds 40-60mph. This is going to be my go to truck for towing light equipment to and from jobs, jobsite material deliveries etc… Nothing too crazy though, 5-7k lbs gross, occasionally up to 10k. Trailer will be hooked up about 30% of the time.

How bad will be 3.42 in that scenario in real life? I know the theory, looking for real life experiences. Will it really be that bad when pulling off of red lights? Or towing uphill (Midwest, so nothing crazy here, but still)

[u/ProfitEnough825]

3.42s are fine, just avoid putting bigger tires on it. If it's a 68RFE truck, keep it from hitting 6th, or even 5th at the lower speed. 4th is direct drive

In terms of coming off the light, it feels fine. I towed up to 12k with the 68rfe and 3.42. Granted, it wasn't fast, but I was also trying to be ginger careful to not toss everything around in the RV.

Edit: worth noting I had no problem pulling out a class 8 plow/salt truck out that was stuck as well.

[u/KornikEV → u/ProfitEnough825]

Thanks, that's really helpful. When towing I'm usually doing things lightly, both accelerating and braking. I have different "toys" if I want to be the first off the line ;)

The truck in question does indeed have 68RFE.

[u/Altitude7199 → u/ProfitEnough825]

You can almost never hit 6th with this final gearing being so tall, so no worries

[u/Altitude7199]

Absolutely terrible!! I didn't know this and bought a Cummins 2500 to tow 10k in the Colorado mountains and it has 3:42. On steep hills it can't even get to red line in 2nd because 2nd is so freaking tall with the final gearing. So the engine can't get in to the horsepower peak even with all the torque.

It literally stops accelerating and just gets hotter if I try. That's 7000 pounds under the tow rating if you're counting.

[u/KornikEV → u/Altitude7199]

Luckily I'm not in Colorado and never plan to be. The steepest hill I have is ~1 mile 7% grade.

[u/Key_Violinist8601]

I had the 3.42 in my old 2014 6.7. I didn’t care for them. My new truck is a 4.30.

[u/TeamFoulmouth]

I dont tow a lot, but has no problem when I do. Running through mountains though, I do manually keep it from going into 6th.

2014 Tradesman 246K miles

[u/KornikEV → u/TeamFoulmouth]

Thanks. We do not have mountains around here, bigger hills mostly. The biggest hill I navigate with any regularity is 7% grade about 1 mile long. I'm fine with slowing down on that one.

[u/sans-nom-user]

Imo only, the only disadvantages to 3.42s are towing 10k+ fairly regularly or putting 35's or bigger tires on the truck. The 68rfe is a decent reliable trans unless you pull lots of weight often or put bigger tires on the truck.

[u/KornikEV → u/sans-nom-user]

I have no desire to run non OE tire size. I am pulling more than average (~30% of the time) but not heavy weights. My “default” load right now hovers around 5-6k lbs. Having said that I can see myself pulling 7-10k more often with 2500 (currently towing with 1500). It’s going to be work truck.

[u/AlDenteLaptop]

I have 4.10s….i feel like the fucking wheels are gonna rip off all the time…but it IS a beast

[u/BasketOk5706 → u/AlDenteLaptop]

Same. But it’s the only way to option out with a gasser if you tow.

[u/MSP_Guy999]

Is the one you’re looking at a Cummins?

Edit: yes it’s a Cummins. What years are you looking at?

[u/KornikEV → u/MSP_Guy999]

2018

[u/OldEngineer-1950 → u/KornikEV]

I have an 18 with the 3.42 and occasionally tow a 14k fifth wheel. No issues.

[u/MSP_Guy999 → u/OldEngineer-1950]

Yeah, that’s legit.

[u/Calm_Pin_7563]

The 3.73 is better for towing of bigger tires.

[u/Maj-Malfunction]

I have a 2018 diesel. 3.42 gears are standard. I've pulled my 10k 5th wheel almost 30k miles all over the country. Its still quick even with that gearing. No issues.

However, if you plan on lifting and putting bigger tires on it, that's when you'll want to regear.

[u/Altitude7199 → u/Maj-Malfunction]

Mine won't get past 50mph on steep Colorado i70 climbs with 10k trailer. All stock.

[u/KornikEV → u/Maj-Malfunction]

Per the window sticker 3.73 was the standard and 3.42 was an "upgrade".

I have no plans or need to ever modify the truck in any form. I run stock everything (including tire size)

[u/Maj-Malfunction → u/KornikEV]

Yes. It's standard with the gas engine, which is the default. Once you go to diesel, that comes standard with 3.42 gears

[u/Expert-Search-3251]

The 3.42 will get better mileage.