Just wanted to get some opinions on the axle ratios for towing. I am looking for an '07 3500 Mega Cab in the Khaki color with the 4.10 axle ratio. Impossible to find. Found one that is perfect and is a great deal (invoice minus $3500 rebate), but just doesn't have the 4.10 gears.

I'm going to be towing a 37ft 5th wheel that weighs 11,500 pounds bone dry and empty. The 4.10 gears allow you to tow 15,850 andwith the 3.73 only13,850. I'm wondering if I would be ok with the 3.73 ratio, but I would be pushing or exceding the limits once my truck and trailer are loaded with gear and people. Any thoughts? The gears just allow the engine to rev higher, but it seems this would mostly be helpful when starting out towing, as once you are moving you can use lower gears in the trany.

Has anybody swapped out the gears in their truck that could tell me about how much it would cost to put the 4.10 in the truck I found?

I have heard about people just putting smaller tires on their trucks to give them a higher axle ratio, has anybody had any experience with this?

 

The 3.73 should be ok as you are not towing the camper every day, just go easy on the pedel and if a cruese the trany hunts gears take it out of OD.
I pulled 10,000lbs from Fl to Chicago back in 1980 with a Chevy 1/2 ton 3.42 gear and the old Chevy 5.7 deisel, (110hp) other than having to use 2nd gear on the auto climing Mount Eagel their was no problem.

 

I think you'd beok with the stock gears for occasional towing, however if you find you need them, or just want the better performance,the gears will cost you around $200 per set and since the truck is an '07 if you had it done fairly soon you could get away with a minor install kit as opposed to a major one, saving a little cash there. If it's a 4x4 you're probably looking at about a grand, installed & out the door. A 4x2 would be $500-$600. If you choose to do this, I would HIGHLY recommend finding a reputable shop, one that has a tech with good experience changing gears. These forums are loaded with horror stories of destroyed rear ends form people attempting to do it themselves or having a mechanic without specific gear change experience doing the job.

 

My brother pulled a 5th-wheel and a boat behind his 2000 2500 TCD with 3:55's and it pulled no problem. This is Colorado driving over the mountains. I think that since the TCD puts out its torque at such low RPMs, you really dont need the higher gear ratio.
He has never had any problems with it. Just as an FYI - this weekend he took his 3000 lb cabover and and towed his 3500lb boat over Berthood Pass and I dont think he ever exceded 2300 rpms in 3rd gear. It never bogged down. I think the TCD compesates the lower gear ratio.

 

My advice is to always over-engineer your truck. Get the 4.10s! This is a major purchase decision, and one you will be living with for a long time. Also, the 4.10 option is dirt cheap compared to buying the gears and having them installed yourself. I plan on buying a 3500 QC, 4x4 soon, and I'm going against what most everyone else (salesman in particular) recommends and getting 4.10s and the $490 side-curtain airbags (also a hard combo to find). Because it's my money, my truck, and I want the most towing capacity possible for any future trade ups to a larger trailer. Right now, my trailer only weighs in around 8000# wet. I would just option it out on Kelley-Blue Book, and place an order for it with the fleet manager.