Regearing axles
Logistics Pro
Joined: May 2011
Posts: 4,832
Likes: 668
From: Maine
They don't build SRW trucks with 4:10 or 4:30 gears with the 6.7 engine.
Not sure what stock size is, but if they were 31.5" tall as stated in another post, going to 37" is a 17.5% change in gear ratio. Going to a 4.10 ratio is a 15.5% change and won't quite get him back to stock. 4.30 is 21.1% change and will be a little lower geared than sock but still turning a heavier tire. His attached quote shows it's a 2018 so he's got the 6spd not the 10spd transmission too. For towing and if he does some off roading I think he will be fine with 4.30. Only drawback for me in that scenario is the new carrier cost if needed.
Not sure what stock size is, but if they were 31.5" tall as stated in another post, going to 37" is a 17.5% change in gear ratio. Going to a 4.10 ratio is a 15.5% change and won't quite get him back to stock. 4.30 is 21.1% change and will be a little lower geared than sock but still turning a heavier tire. His attached quote shows it's a 2018 so he's got the 6spd not the 10spd transmission too. For towing and if he does some off roading I think he will be fine with 4.30. Only drawback for me in that scenario is the new carrier cost if needed.
Hotshot
Joined: Mar 2017
Posts: 10,163
Likes: 1,373
From: Chaz
His stock size is 34.1. 4.10 is more than enough. I would do that and an elocker up front. I am keeping my eye out for a clean 2018-19 platinum in Magma to build and this is my plan.
Just get a 350 dually 3.55 gear. Mine was great.
If you need more capacity than that truck has then you need 4.10 or 4.30; and that is available in a DRW pickup. 3 gear choices in the diesel.
Yeah you need to run a tow safe tune if you are pulling long distances. I pull a skid steer with mine but its local, flat, and I am easy on the throttle. It will whip around that 14-15k trailer like there is nothing back there if I want to fugg up the transmission though; it wouldn’t be worth the headache of moderating all that out on the open road. Similar truck to yours but little shorter tires on stanced 22s and a king ranch.
If you need more capacity than that truck has then you need 4.10 or 4.30; and that is available in a DRW pickup. 3 gear choices in the diesel.
Lead Driver
Joined: Feb 2022
Posts: 7,975
Likes: 4,048
Its the axle used, only a couple companies make the ring gears to fit. I would have probably regeared to 3.73 if there were any available. You can't even replace the carrier for different ratios, just not made. Quite happy with my F350 DRW with 3.55 gearing, does everything I need it for.
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4wd Low
Joined: Jun 2014
Posts: 14
Likes: 4
From: Mesa, AZ
Hey folks,
Sorry for the delay, I did get it regeared with 4.30 and yes, I needed a new carrier. I paid $4100 out the door which was much better. She drives better and it's more fun towing now, I need to do a long trip again and see what the trans stays at. My most reset pre gear, I was hitting 240 degree temps with only 10k in tow from AZ to Cali which Ford claims those are reasonable temps, I was doing 75-80 mph which may have contributed to higher heat. Now, locally at 65 mph empty, I am at 1800rpm which should be the right at the max power of this engine if not mistaken which would be nice for towing at those speed.
Since the truck is tuned, do I need to have it retuned for the gear change or leave it alone? My rough country/hypertech inline speedometer calibrator sets my speed at 12 mph lower than what it really is even after adjusting for the new gears so I took it off and now i'm only 2-3mph off.
Sorry for the delay, I did get it regeared with 4.30 and yes, I needed a new carrier. I paid $4100 out the door which was much better. She drives better and it's more fun towing now, I need to do a long trip again and see what the trans stays at. My most reset pre gear, I was hitting 240 degree temps with only 10k in tow from AZ to Cali which Ford claims those are reasonable temps, I was doing 75-80 mph which may have contributed to higher heat. Now, locally at 65 mph empty, I am at 1800rpm which should be the right at the max power of this engine if not mistaken which would be nice for towing at those speed.
Since the truck is tuned, do I need to have it retuned for the gear change or leave it alone? My rough country/hypertech inline speedometer calibrator sets my speed at 12 mph lower than what it really is even after adjusting for the new gears so I took it off and now i'm only 2-3mph off.
Last edited by C.Andrade; Feb 4, 2026 at 10:35 PM.
Fleet Mechanic
Joined: Apr 2015
Posts: 1,641
Likes: 507
From: Phelan CA
Hey folks,
Sorry for the delay, I did get it regeared with 4.30 and yes, I needed a new carrier. I paid $4100 out the door which was much better. She drives better and it's more fun towing now, I need to do a long trip again and see what the trans stays at. My most reset pre gear, I was hitting 240 degree temps with only 10k in tow from AZ to Cali which Ford claims those are reasonable temps, I was doing 75-80 mph which may have contributed to higher heat. Now, locally at 65 mph empty, I am at 1800rpm which should be the right at the max power of this engine if not mistaken which would be nice for towing at those speed.
Since the truck is tuned, do I need to have it retuned for the gear change or leave it alone? My rough country/hypertech inline speedometer calibrator sets my speed at 12 mph lower than what it really is even after adjusting for the new gears so I took it off and now i'm only 2-3mph off.
Sorry for the delay, I did get it regeared with 4.30 and yes, I needed a new carrier. I paid $4100 out the door which was much better. She drives better and it's more fun towing now, I need to do a long trip again and see what the trans stays at. My most reset pre gear, I was hitting 240 degree temps with only 10k in tow from AZ to Cali which Ford claims those are reasonable temps, I was doing 75-80 mph which may have contributed to higher heat. Now, locally at 65 mph empty, I am at 1800rpm which should be the right at the max power of this engine if not mistaken which would be nice for towing at those speed.
Since the truck is tuned, do I need to have it retuned for the gear change or leave it alone? My rough country/hypertech inline speedometer calibrator sets my speed at 12 mph lower than what it really is even after adjusting for the new gears so I took it off and now i'm only 2-3mph off.
More Turbo
Joined: Aug 2025
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My customer, a temp and pressure switch manufacturer, went out of buisness years ago due to unfair trade practices.
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