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Discussion Starter · #1 ·
97 F350 CC SRW 8' bed. 3.55 limited slip now. The better half and I are considering a new 5th wheel camper. Found a few between 8-9K pounds. According to the chart in the owners manual I can pull up to 9900 with my current set up. If I switch to 4.10 I step up to 13900. Tires are factory 235/85 16. I'm worried about hills n bridges with anything over 10K. Will the switch hurt my normal driving mileage much? I'm getting 19-21 now. Also, what will I need to reprogram the odometer difference?
 

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Make the switch. Will tow much better. Get the highest weight rated tires you can find and have fun. 2wd right?
 

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I would see how the trucks tows before I went to a gear swap. You also have to ask yourself what else are you doing with the truck. If it is just intended to tow your trailer then by all means look at the gear swap, but if it is a daily driver you will need to decide if you want a truck set up to tow or one that will tow what you need, perhaps with a little bit less of performance.
 

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Probably cheaper to find an entire used rear axle than to swap gears. Not sure I'd be scared of 10,000 lbs and 3.55.
AaronSEIA
 

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10k is nothing with 3.55's and 235 tires. It's not worth the trouble for the gear or axle swap. If you find the EGT's are getting too high turn off overdrive on the hills. If you go to 4.10's you are going to lose at least 2 mpg unless you keep it under 55-60 everywhere you go.
 

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I get 20.7 mpg at 55 mph with my 97 F350 4:10 geared dually. At 62-65 I get 17-19 mpg. At 72-75 I get 12 mpg. Towing 9000-15000 I get between 10 and 13 mpg at 62 mph.
 

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Discussion Starter · #7 ·
I have always used MichelinLTX E load range 10 ply. In fact I just got a new set. I e pulled 7K before and I have to stay in the turbo on the road. A little tough to get it moving. I don't like towing under 1850-2000 rpms. Bu that was a tag trailer not 5th wheel. I have a 3 position chip(can't remember what brand). Have a pretty big trans cooler also
 

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Discussion Starter · #8 ·
Forgot to add yes it is 2WD. What rpms are you turning at 70 with 4.10'a? I normally drive 75-80 unloaded. Don't tow often. Wrapping up a restored '72 Buick Gran Sport 455 that I will be towing to the track some
 

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I have a 97 f350 4.10 srw 4wd with 146,000 miles on it. It has a Dana 60 up front and a 12 bolt Ford 10.25 in the rear. I would consider a swap. How many miles are on your rig? When would you consider doing this; it's getting cold in NE Wisconsin.
 

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Discussion Starter · #10 ·
I have 250k miles . I'm in the Deep South so the weather won't be an issue. I love the way the 3.55 drives but I'm skeptical of the way it will tow 10k plus.
 
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