Gears
Veteran
Joined: Feb 2010
Posts: 296
Likes: 1
From: East TN
And what was this big difference, any ET slips or did one just 'feel' faster?
All Star
Joined: Jun 2009
Posts: 975
Likes: 0
From: San Antonio, TX
Depends if you add the LSD unit (3.92 comes with one, 3.55 & 3.21 doesn't). Just swapping the gears is around $300 and labor will run around $400, plus there's the rebuild kit which runs $75. Of course that's all for the 4x2. If you've got a 4x4, then double that price since you have to do both axles.
All Star
Joined: Jun 2009
Posts: 975
Likes: 0
From: San Antonio, TX
G2 OEM. They're just a little more than the regular G2 and the Superior brand, but they're suppose to meet all the OEM specs and not have the higher level of noise some after market ring and pinions have. There were a couple of other brands I was looking into, but since I'm a gear noob, I just took the advice of some co-workers that have done swaps and were happy with the results.
Veteran
Joined: Aug 2007
Posts: 497
Likes: 0
From: HOUSTON,TEXAS
(My truck will be in the shop all day Thursday getting 4.10s, Aurburn LSD, and the R/T torque converter. )
some one is tired of playing around.................
let us know how you like it, as if you wouldnt....
congrats
some one is tired of playing around.................
let us know how you like it, as if you wouldnt....
congrats
Record Breaker
Joined: Dec 2008
Posts: 1,605
Likes: 1
From: VA
It depends if you're just putting one in the rear or both diff's and which one you get. If you're swapping gears then there shouldn't be any more labor in swapping the carrier for an lsd except the cost of the lsd carrier and the new bearings.
All Star
Joined: Jun 2009
Posts: 975
Likes: 0
From: San Antonio, TX
The Auburn I bought was $414. Mine is a 2 wheel drive, so I only had to buy one. For yours, you'll need two, front and rear.
Chambers is right, the shop you use shouldn't charge for install of an LSD if you're getting gears put in at the same time. They're taking everything apart to change the gears, so sticking the LSD back in as they reassemble shouldn't cost extra.
Chambers is right, the shop you use shouldn't charge for install of an LSD if you're getting gears put in at the same time. They're taking everything apart to change the gears, so sticking the LSD back in as they reassemble shouldn't cost extra.
Champion
Joined: Dec 2007
Posts: 3,563
Likes: 0
From: Ontario, Canada
This is something that relies precisely on your type of driving.
We have the 3.21 diff (which most everyone here will say is a "dog" or too slow, whatever) but for what we do (95%+ highway driving) it's the best option. We hardly ever tow, and when we do it's a motorcycle on a trailer (so maybe 1000lb's max).
The 3.21 diff gets GREAT highway mileage but yes, it will cause your around town mileage to suffer, and yes it is more than likely slower off the line than the other diffs.
But, if all you do is sit on the highway at 70-80mph, then this is the diff for you. The diff gears the truck so that 2nd gear is almost perfectly in line with the governor. The truck is limited to 105mph, and the truck is about 200-300RPM's away from redline in 2nd gear when it hits that limiter. Makes for great passing at highway speeds. The truck also sits at less than 2000RPM at 85mph, which is great for mileage.
I averaged 18.2mpg going about 90mph for 10 hours with some mixed in city driving (we do have a tonneau though). We got 23.6mpg going 70mph on the freeway only.
If you do a lot of combined (like 50/50 hwy/city or even 70/30) you might want to opt for a 3.55 diff. But if you do a TON of highway driving, then the 3.21 diff might be something you want to look into.
If you do primarily city driving, the the 3.92 might actually get you better mileage.
This is my one complaint about the truck. Other than go through all this BS with the diff ratio's, they should have thrown a 6 speed into the truck and not worried about the gearing. With a 6th gear we could have had the first 3 gears as short as a 3.92 diff and the final drive still as tall as a 3.21 diff.
We have the 3.21 diff (which most everyone here will say is a "dog" or too slow, whatever) but for what we do (95%+ highway driving) it's the best option. We hardly ever tow, and when we do it's a motorcycle on a trailer (so maybe 1000lb's max).
The 3.21 diff gets GREAT highway mileage but yes, it will cause your around town mileage to suffer, and yes it is more than likely slower off the line than the other diffs.
But, if all you do is sit on the highway at 70-80mph, then this is the diff for you. The diff gears the truck so that 2nd gear is almost perfectly in line with the governor. The truck is limited to 105mph, and the truck is about 200-300RPM's away from redline in 2nd gear when it hits that limiter. Makes for great passing at highway speeds. The truck also sits at less than 2000RPM at 85mph, which is great for mileage.
I averaged 18.2mpg going about 90mph for 10 hours with some mixed in city driving (we do have a tonneau though). We got 23.6mpg going 70mph on the freeway only.
If you do a lot of combined (like 50/50 hwy/city or even 70/30) you might want to opt for a 3.55 diff. But if you do a TON of highway driving, then the 3.21 diff might be something you want to look into.
If you do primarily city driving, the the 3.92 might actually get you better mileage.
This is my one complaint about the truck. Other than go through all this BS with the diff ratio's, they should have thrown a 6 speed into the truck and not worried about the gearing. With a 6th gear we could have had the first 3 gears as short as a 3.92 diff and the final drive still as tall as a 3.21 diff.
