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07-17-2015, 11:39 AM
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#1
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4 Rivet Member
2011 30' Classic
2007 25' International CCD
1993 32' Excella
Largo
, Florida
Join Date: Nov 2013
Posts: 355
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3.31 or 3.73 Differential
On the 6.7 F-250, which is the preferred rear end differential ratio?
Thanks,
>>ron<<
__________________
2015 GMC Denali 2500, 4x4, Duramax diesel, Topper, Pro Pride 3 P, Sendel 16" with Michelin LTs, one Yellow Labrador Retriever (AS security)
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07-17-2015, 12:13 PM
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#2
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Moderator
2017 26' Flying Cloud
Alamo Heights
, Texas
Join Date: Aug 2006
Posts: 8,500
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For '16, I don't think the 3.73 is even available on a 250 with the diesel, you have to get into a 350 DRW. All their specs list is 3.31 and 3.55 for the F250 with the 6.7L. Even for a 30' Classic I'd think that 3.31 would do OK with 860 lb-ft of torque at 1600 RPM, and the 3.55 would probably drag it pretty well even without wheels on the trailer.
__________________
— David
Zero Gravitas — 2017 Flying Cloud 26U | WBCCI# 15566
He has all of the virtues I dislike and none of the vices I admire. — Sir Winston Churchill
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07-17-2015, 01:21 PM
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#3
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3 Rivet Member
2010 28' Flying Cloud
Slidell
, Louisiana
Join Date: Nov 2009
Posts: 125
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Have 6.7 with 3.31 towing 2010 28ft FC usually with about 800 lbs of tools & 8.5 genset in bed. Effortless tow even across Rockies but minor concern is 1st gear wheel spin on quick starts from traffic lights, especially if damp or Sandy pavement, or when turning while starting from stop and occasional tire chirp on 1-2 shift. Don't need any lower gearing.
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07-17-2015, 01:35 PM
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#4
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Moderator
2017 26' Flying Cloud
Alamo Heights
, Texas
Join Date: Aug 2006
Posts: 8,500
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I just happened upon an article about Ford's commercial vehicles... the F650 and F750 also use the 6.7L as one of their powerplant options... and in the hottest of the 3 tunes it's putting out 330hp and 725 lb-ft. of torque. This in a truck that's going to do WAY more work than probably 95% of F250s on a day-to-day basis. It speaks to what ludicrous overkill the numbers battle between the big 3 has become... the F250 is tuned for 440 hp and 860 lb-ft of torque. I wonder how much longer they'd last tuned like an F750.
__________________
— David
Zero Gravitas — 2017 Flying Cloud 26U | WBCCI# 15566
He has all of the virtues I dislike and none of the vices I admire. — Sir Winston Churchill
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07-17-2015, 01:45 PM
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#5
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TinCan
2016 30' Classic
Apache Junction
, Arizona
Join Date: Aug 2011
Posts: 880
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I have read on several Ford forums that the 3.31 rear end for the F250 diesel works just fine. The only difference is perhaps just a tad better mpg. I have ordered my Lariat with the 3.31's
__________________
TinCan
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07-17-2015, 01:48 PM
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#6
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4 Rivet Member
2011 30' Classic
2007 25' International CCD
1993 32' Excella
Largo
, Florida
Join Date: Nov 2013
Posts: 355
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Quote:
Originally Posted by DKB_SATX
For '16, I don't think the 3.73 is even available on a 250 with the diesel, you have to get into a 350 DRW. All their specs list is 3.31 and 3.55 for the F250 with the 6.7L. Even for a 30' Classic I'd think that 3.31 would do OK with 860 lb-ft of torque at 1600 RPM, and the 3.55 would probably drag it pretty well even without wheels on the trailer.
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The reason i am asking is that I am looking at a 2012, F-250 XL that comes with the 3.73. Appreciate your response.
>>ron<<
__________________
2015 GMC Denali 2500, 4x4, Duramax diesel, Topper, Pro Pride 3 P, Sendel 16" with Michelin LTs, one Yellow Labrador Retriever (AS security)
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07-17-2015, 02:12 PM
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#7
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Rivet Master
1960 22' Safari
in the wilderness
, The great Mojave Desert
Join Date: Jun 2006
Posts: 4,077
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I like 3:73's in my 4X4's. On a straight street truck either is just fine with a Powerstroke. It wouldn't make a difference to me.
__________________
I'd rather be boon docking in the desert.
WBCCI 3344 FCU
AIR# 13896
CA 4
Yes, we have courtesy parking for you. About an hour North of Los Angeles.
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07-17-2015, 08:05 PM
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#8
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Full time Airstreamer
2014 30' FB FC Bunk
Anywhere
, USA Living.Somewhere.Yonder
Join Date: Jan 2014
Posts: 1,359
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Quote:
Originally Posted by DKB_SATX
I just happened upon an article about Ford's commercial vehicles... the F650 and F750 also use the 6.7L as one of their powerplant options... and in the hottest of the 3 tunes it's putting out 330hp and 725 lb-ft. of torque. This in a truck that's going to do WAY more work than probably 95% of F250s on a day-to-day basis. It speaks to what ludicrous overkill the numbers battle between the big 3 has become... the F250 is tuned for 440 hp and 860 lb-ft of torque. I wonder how much longer they'd last tuned like an F750.
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I agree and would gladly take any of the F650/750 versions if it meant better gas mileage (i assume longevity is a given). Here they are.
• 270 horsepower/675 lb.-ft. torque
• 300 horsepower /700 lb.-ft. torque
• 330 horsepower/725 lb.-ft. torque
__________________
@living.somewhere.yonder | Instagram
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07-17-2015, 08:24 PM
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#9
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Rivet Master
2002 30' Classic S/O
Garden Valley
, Idaho
Join Date: Jul 2010
Posts: 1,631
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You won't be disappointed in the 3.73, but if I was looking at a new 6.7, I would go with the 3.55 if I was in the mountains. Otherwise, the higher ratio (lower number) will be fine.
__________________
2008 F-250 4X4 Lariat V-10
2002 Airstream Classic 30' w/SO #2074
2007 Kubota 900 RTV
1996 Ford Bronco
2007 Lincoln LT
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07-17-2015, 09:14 PM
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#10
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4 Rivet Member
Currently Looking...
sequim
, Washington
Join Date: Apr 2014
Posts: 301
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3.55 is in my f350. works just great and a good pairing with all of that torque and hp.
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07-19-2015, 04:16 PM
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#11
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2 Rivet Member
2018 25' International
2008 16' International
Forest Knolls
, California
Join Date: Jul 2014
Posts: 49
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3.31 or 3.73
I have a 2015 F250 6.7 with the 3.31 ratio and I like any advantage I can get for maximizing fuel economy. Towing an AS25FB is easy with this truck. Here in California with the Sierras to climb, I find that I just keep the tranny in 5th at 50-55mph on the climbs and the engine revs nice and easy, 1600-1800 RPM, just above peak torque. As an old trucker, letting that engine work just above peak torque let's it run easy on 6% grades at altitude which may not be necessary, but makes me happy.
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07-20-2015, 07:00 AM
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#12
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TinCan
2016 30' Classic
Apache Junction
, Arizona
Join Date: Aug 2011
Posts: 880
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As an old trucker myself I loved my Cat's. The lower the RPM the better they pulled and with decent fuel economy. Hopping the same will be true with my 2016 F250 which is on order. Big changes coming with the 2017's but just can't wait another year.
__________________
TinCan
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