Fifth Wheel Towing Limit and Axle Ratio 3.73 vs 4.10

Run away from it. I owned a 6.0 for 8 years, did all the bulletproofing, put 10k in the motor and I'd still never own another. Will probably never own another Ford. I can promise you if you think that replacing the egr instead of deleting is a viable option, you've got a steep learning curve ahead.

With that said, you'll be just fine with 3.73. I would want a limited slip, but I can tell you the factory one is not very good. I ended up pulling the factory limited slip out, and putting in a Detroit trutack great driven limited slip. I built rear end for a while so it wasn't that costly for me to do. It's worlds better that the factory clutch pack limited slip.

Take the advice for what it's worth. I've been there, done that, had the cab pulled multiple times, even had to replace the heads with o-ringed heads. Never again. It was miserable towing, wondering where I was going to break down next with my camper and boat in tow. I bought a Duramax last year and haven't looked back.

Had a '03 F250 SD, 6.0 PSD, CC,4x4,sb. Added: 50 Transferflow replacement tank, Banks Monster Exhaust and had the FICM repaired and beefed up some. Ordered it w/ the 3.73, camper & tow pkg. Towed a '06 Cedar Creek Silverback 33 LBHTS. Dry wt of 5er was 10,800, max wt of 5er was 13,800. Ran pretty much at 13,000 for 5er wt. Truck did a very good job in towing and stopping the rig. Ave 10.5 mpg's at 70 mph towing w/ A/C on. 2,000 rpm's was peak torque for the motor and that equated to 70 mph, so that's where I ran it. Believe peak HP is 3200 rpm's. Really liked the truck, but she started to cost $$ w/ box rust/replacement, manifold's cracked. So rather than put a lot of $$$ into a vehicle that was 12+ years old and costs of said items would be close to vehicles worth, traded it in for new ride. Kinda miss the "rattle" of that 'ol gal's motor.

scottkeen wrote:

shadows4 wrote:
I think either will do the job. Now before all the 6.0 bashers get here, just educate yourself about the 6.0. It is an awesome towing machine when running right.

I've been educating myself about the 6.0L for almost a year.

I think I've watched every PowerStrokeHelp video out there that Bill has made, read the BulletProofDiesel website and FAQ and actually called and spoke with them (very helpful!). I've also watch videos of 6.0L full-time RV'ers LoLoHo and Jared Gillis both break down with the EGR problem.

I've already discussed with my regular mechanic shop that I will be getting a 6.0L diesel and will be looking to replace (NOT delete!) and upgrade the EGR and head studs shortly after I get the truck.

Once the work has been done, my understanding is that the 6.0L is a 300K, 400K, 500K or more truck.

I was a Ford man for 54 years, time to buy a diesel I chose to get a Cummins in a Dodge wraper. Best decision I ever made! Currently at 301,000 miles. Still towing a 12,360# GVWR 5er.

I owned a "bulletproof" 2003 F-350 6.0L 4.10 dually; I would pass on the 6.0L and go with a 7.3L if set on a Ford. Good luck with getting 500k miles out of a 6.0L without spending a zillion dollars to get it there....

I have the same year truck you are thinking about except it is a SRW. My 5th wheel weighs 12600lbs loaded and my truck pulls it fine with a 3.73 axle. And I also pull doubles with a 2800lb boat/trailer behind at times. Still does well, and I do much of this in Colorado! Big hills to pull.
You should be okay with what you are considering, IMO. As far as limited slip, if you get a truck that has it fine, if not you still will be okay. Mine has it but I cannot think of a situation I have been in that needed it while towing. In the winter when just driving the truck it has been handy.

Worst case you can swap gears for $1,500 (per axle). For all I know you could choose 4.30+ if conditions dictate. Limited slip is only needed in low speed low traction situations. Either way carry a tow strap if you will be camped on mud, sand, grass or snow. Although should not be a huge concern with 4WD.

Agreed with others on the 4.10 unless it's also going to be driven empty a lot. 14,3 isn't light and you will quickly get used to the 6.0 wanting to scream (or at least sound like it is). In tow/haul mode, 3,000RPM is the shift point.

We have a nearly identical truck but with the 4.30 gears. It's great for starting off but I would've like the 4.10's at most for cruising (4.30's ~2300RPM @ 70MPH) and it's large hills here in WI. no real mountains.

I'll only touch on the 6.0. My opinion on the 3.73s are pretty much in line with everyone else, you included. good economy and engine is strong enough to make up for higher gears.. Different story if a lot of hills/mountain towing though. If you do go with, be prepared for running lower trans gear/higher rpms. Limited slip is really nice when needed, if you are sticking to comercial campgrounds where mostly paved/gravel. I wouldn't worry too much. With the 4.30's (and supposed LS) i was still only spinning one wheel when we got in a weird spot on the grass. I just readjusted my angle.. you still have 4x4 if really needed.

As for the 6.0 itself. It's great when it works. Ours is only partially "bulletproofed". EGR delete, replaced oil cooler, replaced coolant with xerex, installed ipr coolant filter, dummy plugs, stand pipes, verified stc fitting is updated version, cleaned exhaust side of turbo. Only thing not done (and it's the big one) at this point is studs/gasket and I fear it's coming.

EGR delete - Fixes blown egr cooler flash boiling coolant which leads to HG/head issues. At least get upgraded BPD style if keeping it.
Oil cooler - Replace if/when replacing EGR cooler. Gets gunked up from ford gold coolant and **** left from engine assembly process
STC fitting - Verify/replace if/when replacing EGR/oil cooler. If older style, they can fail causing long starts/crank or no start.
Coolant - Xerex (ZXED1) replacement after flush. I read it was highly recommended along with a few others. This was just my choice of replacement.
Coolant filter - My extra piece of mind to help protect oil cooler from any remaining **** getting stuck in oil cooler.
Dummy plugs - Failed o-rings lead to long starts/crank or no start., replace with oem with poly washers (comes in kit)
Stand pipes - Failed o-rings lead to long starts/crank or no start., replace with oem with poly washers (comes in kit)
Exhaust side of turbo cleaning - Just used wire brush to clean off soot. This was causing us to overboost due to vanes not being able to work properly. Also found unison ring severly worn (cause over/under boost) along with worn actuator (cause over/under boost)



If you are able to do the proper bulletproof, make sure to have the heads checked for flatness otherwise you will be back. I've only read positive reviews about BPD's EGR cooler and it's about the same as a oem replacement. Along with any research your still doing, I'd recommend checking out powerstroke.org. They've helped me quite a bit.

Oh, and don't be afraid to stomp on it, on ramps.. etc. they don't like to be babied. I have pics of the turbo proving it. :)


Sorry for long post, hope it was at least somewhat helpful.

I would get the 4.10 ratio if this is mainly a tow rig. If you will drive it around empty every day when not towing then probably the 3.73 would be better.
You absolutely want the limited slip. They make a big difference in muddy, snow, generally low traction conditions. There really isn't much of a downside with a properly functioning limited slip.
I'm glad you've read up on the 6.0. We had two at work. Even when they weren't in the shop they were loud, hard to start, and handled badly.

I have a 35' 5er of about equal weight. Towed it with a stock 2007 F350 6.0 with 3.73 and it towed it fine, even over Colorado mountain passes. Now tow it with a 2012 F350 6.7 with 3.55 and it tows it even better.

scottkeen wrote:

shadows4 wrote:
I think either will do the job. Now before all the 6.0 bashers get here, just educate yourself about the 6.0. It is an awesome towing machine when running right.

I've been educating myself about the 6.0L for almost a year.

I think I've watched every PowerStrokeHelp video out there that Bill has made, read the BulletProofDiesel website and FAQ and actually called and spoke with them (very helpful!). I've also watch videos of 6.0L full-time RV'ers LoLoHo and Jared Gillis both break down with the EGR problem.

I've already discussed with my regular mechanic shop that I will be getting a 6.0L diesel and will be looking to replace (NOT delete!) and upgrade the EGR and head studs shortly after I get the truck.

Once the work has been done, my understanding is that the 6.0L is a 300K, 400K, 500K or more truck.

Do not replace and upgrade the EGR...deleate it.