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Discussion Starter #1
Going to regear my truck and need you help.

What gear ratio should I run? I'm thinking 4.10s.

I do not ever intend to run anything smaller than a 37" tire.

What brand is most quiet? From what I read AAM is closest to factory and preferred.

Did a search on telephone number to order and could not find....anyone have a number?

I have the factory limited slip....should I upgrade or factory is perfectly fine...I do not off road.

What is the break in period? I read 500 miles and 55 mph...

I'm in the gulf coast area....anyone have any recommendations on installers?

Thanks for reading and thanks for all the help.
 

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Anything over 4.10 for 37’s is unnecessary.

AAM and G2 and nitro get my vote for silence.

Break in is 500. Avoid sustained highway speeds for your first trip.
 

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4.10
 

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The factory limited slip sucks! No getting around the cheap copy of a Detroit True Trac. If your happy with it, leave it. I’m not, I like the clutch style sure grips, work all the time and you don’t need to use both feet to get it to work. Although the diff fluid requires an additive, no biggie.
 

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For others reading this, I’ll pepper the opinions with “it depends on your transmission.”

G56 has a higher (numerical) OD than the autos.

That said, for your specific application, if I towed occasionally I’d go 4.10. If I regularly towed heavy, 4.56.

That said, if I regularly towed heavy, I probably wouldn’t be running 37’s. My 2 cents.

I think the guys have covered your other questions.

Either route, I think you’ll be happy.
 
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I am going to do 4.10s. I only have 35s now, but will probably upgrade to 37s. If not, I will enjoy the better towing capability of the 4.10s.

AAM are factory gears, that is what I will be replacing with
 

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4.10 - 68RFE or 69AC

Doesn't matter the trans, they both benefit from the 4.10 gear ratio and 37's.
 

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Unless you're towing really heavy I'd say 4.10 also.
 

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Discussion Starter #10
Thanks for all the replies.

Couple more questions.

What rear end do I have? 11.5 or 11.8? My truck is a 3500 srw.

Also....any of you ever thought about 4.30s or 4.10 the better route?
 

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You have an 11.8 however a 11.5 will fit. Both are in the same 14 bolt housing. They just use different bearings for their associated R&P
 

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Also don’t go getting all caught up in the numbers race.

4.10 vs 4.30 vs 4.44 vs 4.56

I see guys on here all the time debating over which is best. Trust me when I say this. Your rear end (your butt) will not feel a difference between those 4. The only difference will be final RPM +/- 100-300 RPM.

I’ve had 4.56 in my last 2 trucks and I now have 4.10’s. Guess what, they feel the same. The only thing you gain by going marginally higher is a higher final RPM, which as mentioned earlier is only suggested if you want to “comfortably” tow heavy 24/7.

But even then in order to get your power band back all you need is 3.8 something. Since none such gear exists the next best step is up, not down, that being 4.10. So now since you have more gear than you need, 4.10 is plenty to tow max #’s these trucks are capable of towing. The only reason go higher gear is to tow more “comfortably” not more weight.
 

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Thanks for all the replies.

Couple more questions.

What rear end do I have? 11.5 or 11.8? My truck is a 3500 srw.

Also....any of you ever thought about 4.30s or 4.10 the better route?
You have an 11.8 however a 11.5 will fit. Both are in the same 14 bolt housing. They just use different bearings for their associated R&P
are you sure??
I have an '18 3500 SRW with Aisin, my build sheet says 11.5"
I have been wondering the same thing, is it 11.5 or 11.8 :confused:
 

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I see guys on here all the time debating over which is best. Trust me when I say this. Your rear end (your butt) will not feel a difference between those 4. The only difference will be final RPM +/- 100-300 RPM.
And this is the truth.
 

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Discussion Starter #17
So 11.5 it is?

I ordered my AAM gesrs through East Coast and they told me my rear end was 11.5...

I got 4.10s too btw.
 

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i have 4.56's

i guess the only complaint is running nearly 2k rpm's at 70
 

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I had 4.10's installed in my truck for 35's, if I were going to run 37's all the time I would go 4.30. I live in the hills and use my truck to haul my equipment and livestock and with the extra weight and circumference of 37's, 4.10 wouldn't be enough gear in my opinion. I'm not a mechanic, I just know what I want/need out of my truck.
 
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