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3.55 vs. 3.73

17K views 23 replies 10 participants last post by  Durapig Eater 
#1 ·
hey guys I'm looking got trade my 2003 7.3l for a 2015 4 door 6.7 the only thing that worries me is the rear end, I have a camper that is about 14,000 lbs but I do not pull it that much....do you all think the 3.55 will be ok? or should I hold out for a 3.73

Thanks!!
 
#3 ·
Not to mention, just a tad bit more HP/Torque then the 7.3L So I doubt you'd even notice the difference.
 
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#14 ·
I have factory 3.73 lsd on my 12 drw 6.7....
I feel it's the perfect gear btw.
 
#7 ·
3:31 or 3:55, if it is a 350 or has the 20" wheels most likely it has the 3:55 gears. the gas engines came with 3:73 or you could order 4:30, my buddy waited 3 months for his 6.2 with 4:30 gears....now he wishes he bought a 6.7 with 3:55

BTW...you put this under the 2017 category, might get better response under the 2011-2016, 2017 has different gearing in some models.
 
#9 ·
so you would not recommend any tunes? I was hoping to at least get it tuned out of using the def fluid if that is even possible, my current 7.3l has a turner from DP tuner but wasn’t for sure (when the time comes) if anybody had any other ideas for tuners or what was recommended
 
#10 ·
I cant help you with the modding, my previous 2011 had over 110k miles and was bone stock never had an issue. my current truck has 100k mile warranty and will remain stock also. Def isn't expensive about 4 gallons every 5k miles or oil change.
 
#13 ·
I found a truck I want. Has all the options but only has a 3:31 gear I plan on getting a 5th wheel soon. I haven't changed a ring and pinion in 25 years. I think I may just get the truck and change gears later. Is it a big expense?
 
#16 ·
Axle code from the sticker on the drivers B pillar, then ask the google or call the parts counter at your dealer.

Ford did drop the 3.73 from the lineup according to the 17 order sheet earlier in this thread.
 
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#17 ·
I have an 11" f350, 3.31 and 20's. pulls equipment everyday 26-30k gross no problems. I deleted it and I am running 60 hp setting, I didn't notice much difference, maybe 1,5-2 mpg. I had 155k on mine and needed a def heater and some sensors, it was a wash on fixing def system or deleting. that was a simple choice! We have 7.3 450 and 550 with 6 sp manuals, 4.88's, 60 hp programs and bigger injectors. They will run with the 6.7, get almost as good mileage, but 6.7 has power all the time and the auto is flat out amazing. Any 6.7 will pull whatever (within reason) you want comfortably and have plenty of power
 
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