3.42 to 4.10 Differential Swap Question

mesaboogie

Original poster
Member
Dec 8, 2011
8
I have a SWB TB with 3.42 gears currently. I want to upgrade to 4.10 gears by swapping out my current differentials rather than buying new gears and having them rebuilt since it seems to be the cheaper option.

So my question(s) is, if i were to replace my rear differential with a 4.10 LWB 8.6" axle, would I also have to change my carrier to match? And if so, would the new carrier have to be from a LWB TB model or could I use a carrier from a SWB TB?

Would my front differential have to work the same way? Coming off of a LWB TB?

The only reason i want the 8.6" over the 8.0" is so I will still have some wiggle room in the future should I choose to go with 4.56 gears.
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
IIRC, the front diff is the same for all the 4x4 trucks.

Finding a complete 8.6" rear with the 4.10 and G80, would be the easiest swap, but the 4.10 gears are going to be hard to find.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
So many things change in the rear, including the axle shafts going from 28 to 30 splines (plus the carrier, plus the end gears), that swapping the entire axle is the preferred route I took. 2 person, 1/2 day job. 4.10 are indeed more rare, and the recyclers know it and raised the prices accordingly. A 4.10 front is the rarest because many of the 4.10 axles went on 2WD trucks. Sometimes I see 4.10 fronts go for double the price of a 3.42.

IMHO, you should so this ONLY if you need the offroad performance for 33"+ tires. Don't do it for any other reason unless you have an excess of money and a shortage of math skills do do the cost/benefit analysis. :wink:
 

djthumper

Administrator
Nov 20, 2011
14,955
North Las Vegas
mesaboogie said:
I have a SWB TB with 3.42 gears currently. I want to upgrade to 4.10 gears by swapping out my current differentials rather than buying new gears and having them rebuilt since it seems to be the cheaper option.

So my question(s) is, if i were to replace my rear differential with a 4.10 LWB 8.6" axle, would I also have to change my carrier to match? And if so, would the new carrier have to be from a LWB TB model or could I use a carrier from a SWB TB?

Would my front differential have to work the same way? Coming off of a LWB TB?

The only reason i want the 8.6" over the 8.0" is so I will still have some wiggle room in the future should I choose to go with 4.56 gears.

To find a 4.10 axle on a 8.6" for a2007 is going to be even more expensive that a pre-2006 axle. You can not use the carrier from an 8" to an 8.6" as they are different sizes.

Even if you bought an EXT axle with an open differential and decided to build it to a 4.10 it will cost almost the same to build directly to a 4.56. Why do the job twice? Work smarter, not harder.
 

nbenjamin

Member
Dec 7, 2011
76
the roadie said:
So many things change in the rear, including the axle shafts going from 28 to 30 splines (plus the carrier, plus the end gears), that swapping the entire axle is the preferred route I took. 2 person, 1/2 day job. 4.10 are indeed more rare, and the recyclers know it and raised the prices accordingly. A 4.10 front is the rarest because many of the 4.10 axles went on 2WD trucks. Sometimes I see 4.10 fronts go for double the price of a 3.42.

IMHO, you should so this ONLY if you need the offroad performance for 33"+ tires. Don't do it for any other reason unless you have an excess of money and a shortage of math skills do do the cost/benefit analysis. :wink:



What about for towing ? would it really improve anything beside tow capacity ?
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
nbenjamin said:
What about for towing ? would it really improve anything beside tow capacity ?
Well, yeah, it would help accel performance from a stop for towing. Just as larger tires hurt the same measurement. Not anything that would normally induce me to spend $1200, plus install if I had to farm it out.
 

fishsticks

Member
Nov 21, 2011
433
You can set up your own gears with $150 in tools from Harbor Freight and some patience. No reason not to do it yourself unless you have nowhere to work on the truck...

If you nee to drive it, do the rear one weekend, and the front the next weekend.

Then you can just buy the cheapest 8.6" axle you can find. You'll be rebuilding it anyway.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
I have been looking for a decent price on 4.10s for long time. Good luck.
 

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