Rear end order option 8.8 or 9.75

[shawizkid]

New to the forum, and recently back into the ford family after 20 years of Gm products.

Anyway, done some searching and looking for some help.
I’m about to place an order on a 2022 xlt 302a sport package w/2.7eb. Trying to decide whether to go with the elock 3.55 (8.8) or elock 3.73 (9.75)

truck will be daily driver, hauling cargo in the bed from time to time, but rarely used for towing.

any thoughts on what to choose and why would be appreciated. Thanks!

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[tony72cutlass's']

I went for the 9.75 because for the price (being the same) why not!! I think it was a couple hundred extra to add the locker in any configuration.

I have found it not to affect my MPG at all. i am getting about 19MPG average with 3.73 gears and the 5.0.

 

[shawizkid]

I went for the 9.75 because for the price (being the same) why not!! I think it was a couple hundred extra to add the locker in any configuration.

I have found it not to affect my MPG at all. i am getting about 19MPG average with 3.73 gears and the 5.0.

Thanks! And yeah the price is very similar. For the 2.7 you have to get the payload package to get 9.75, which is like $1k or something.
But yeah, my biggest concern with the 3.73 is whether the gearing and overall size will cause any noticeable impact on fuel economy. If not then this seems like the way to go.

 

[Baddeal]

I chose 3.73 with e locker for my order because it would be a chore to add it later.
The price for gear/locker/fluid/install will be above the option price if I did it later on. It’s also a whole axle upgrade too, not just gears, so add that cost in too. Mine is a rcsb 4x4 5.0 order though, I wanted maximum fun factor and the price made it a no brainer. Especially after owning a vortech gen 1 lightning build. I’ll still be towing my foxbody around, etc etc etc. and it’ll help with that too.
Also need to take in account if you are going to run taller tires/lift, if so then why wouldn’t you run 3.73s.

 

[Baddeal]

I apologize. I thought it was between 3.31s and 3.73, still the 3.73s though.

 

[Mtnman1]

New to the forum, and recently back into the ford family after 20 years of Gm products.

Anyway, done some searching and looking for some help.
I’m about to place an order on a 2022 xlt 302a sport package w/2.7eb. Trying to decide whether to go with the elock 3.55 (8.8) or elock 3.73 (9.75)

truck will be daily driver, hauling cargo in the bed from time to time, but rarely used for towing.

any thoughts on what to choose and why would be appreciated. Thanks!

The 9.75 is beefier in everyway...even axles are bigger.

I will be adding a plow to mine, just for my drive, and wanted the 3.73/9.75.

 

[KBKEITH]

Thanks! And yeah the price is very similar. For the 2.7 you have to get the payload package to get 9.75, which is like $1k or something.
But yeah, my biggest concern with the 3.73 is whether the gearing and overall size will cause any noticeable impact on fuel economy. If not then this seems like the way to go.

My ‘21 with 2.7EB came with the 9.75 and I do not have the payload package.

Because I have the FX4 option, that allowed me to get the 3.73 with the 2.7. I really do not know why I have the 9.75 axle, though. My ‘16 with the 2.7, FX4 and 3.73 came with the 8.8 axle.

 

[3DogKnight]

I might be wrong on this but I believe the max tow package with 3.55 e-lock is 9.75. When I last had my oil changed, my mechanic as always, let me look at the underside when it was on the lift. It's hard to tell the actual size of the ring gear without opening it up but we both agreed that this is a very beefy diff. I've owned some 60's and 70's muscle cars over the years and the pumpkins on those weren't as big as the one on my truck. Like I said, I could be wrong on this assumption so please correct me if I am. 2021 XLT 3.5 SuperCrew 302a w/max tow package and other goodies.

 

[tony72cutlass's']

My ‘21 with 2.7EB came with the 9.75 and I do not have the payload package.

Because I have the FX4 option, that allowed me to get the 3.73 with the 2.7. I really do not know why I have the 9.75 axle, though. My ‘16 with the 2.7, FX4 and 3.73 came with the 8.8 axle.

From what i understand 2021 onwards, 3.73 gets you the 9.75.

Although if you look at the guide below, it shows 3.73 available on the 8.8, I have not heard of a case of them actually doing this.

 

[Nevadajack]

Thought the 2.7 with 3.73 Locker always brings on the 9.75 in 4x4 or Fx4.
The 3.73 definitely pulls nice on a grade.
3400 miles and 23.9 mpg's.

 

[MTNMN]

Im curious why everyone is voting for him to get the 3.73 when he says in his OP all hes doing is hauling cargo in the bed and very rarely towing.

So you tell him to get the towing axle with the less fuel economy??

The 3.55 is the appropriate axle for this guys usage.

 

[shawizkid]

I might be wrong on this but I believe the max tow package with 3.55 e-lock is 9.75. When I last had my oil changed, my mechanic as always, let me look at the underside when it was on the lift. It's hard to tell the actual size of the ring gear without opening it up but we both agreed that this is a very beefy diff. I've owned some 60's and 70's muscle cars over the years and the pumpkins on those weren't as big as the one on my truck. Like I said, I could be wrong on this assumption so please correct me if I am. 2021 XLT 3.5 SuperCrew 302a w/max tow package and other goodies.

yes max tow is 9.75 but that package is not available w/2.7. Also you can tell by the diff cover shape. There’s pictures online. Basically if it’s symmetrical then it’s the 8.8. If it’s tapered on one side it’s the 9.75. Both are 12 bolt.

 

[shawizkid]

From what i understand 2021 onwards, 3.73 gets you the 9.75.

Although if you look at the guide below, it shows 3.73 available on the 8.8, I have not heard of a case of them actually doing this.

If you get a 2.7 I think you have the option to get the 8.8 with 3.73. If 3.5 or 5.0, 3.73 automatically gets your the 9.75

 

[shawizkid]

Im curious why everyone is voting for him to get the 3.73 when he says in his OP all hes doing is hauling cargo in the bed and very rarely towing.

So you tell him to get the towing axle with the less fuel economy??

The 3.55 is the appropriate axle for this guys usage.

Yep this is kinda why I asked. I’m sure no one will be able to provide any real reliable data, as fuel economy has so many variables. But what I ultimately want to know is how much acceleration and fuel economy are impacted going from the two different gear sets.

I know most peoples opinion is “the more fear the better” but was hoping to hear from some examples from owners which both of these configurations (or more helpfully anyone with experience having had both)

 

[3DogKnight]

yes max tow is 9.75 but that package is not available w/2.7. Also you can tell by the diff cover shape. There’s pictures online. Basically if it’s symmetrical then it’s the 8.8. If it’s tapered on one side it’s the 9.75. Both are 12 bolt.

Sorry I skimmed over the 2.7 EB part of your post. Thank you for posting the shape for me to look at when my truck is on the lift next time. Good info!

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