trailblazer ext to ss rear end swap help

[EXT Blazing]

Hi I was wondering if anyone can give me some information, I have 03 trailblazer ext and want to install the ss rear end into it, I found the complete rear with axles and brakes for cheaper than I can get a lsd for mine, I know that everything will swap over to my brakes and suspension and work but im not sure if my driveshaft will work or need a custom one, or some sort of a adapter. I've seen people that done on the swb trailblazer with no problem but not a ext

 

[The_Roadie]

One (or maybe two?) offroaders did it, but they would be SWB for sure, not EXTs. Not sure the purpose in an EXT. What's your mission? I thought all SS had 4.10s.

Added: If you fill out your profile it would help. Are you 4WD even?

 

[EXT Blazing]

I'm going turbo, and I don't have the factory g80 option as I was looking for a Eaton lsd I came across someone selling the whole rear from a ss for cheaper than a used or new lsd from Eaton, I don't want a locker since they don't really hold up to begin with, so with the added power and since I use the car to tow also i need something strong and reliable. And yes I am 4wd with the 3.42 gears.

 

[jimmyjam]

Hi I was wondering if anyone can give me some information, I have 03 trailblazer ext and want to install the ss rear end into it, I found the complete rear with axles and brakes for cheaper than I can get a lsd for mine, I know that everything will swap over to my brakes and suspension and work but im not sure if my driveshaft will work or need a custom one, or some sort of a adapter. I've seen people that done on the swb trailblazer with no problem but not a ext

the alterations for ext vs swb are the same: shorten drive shaft and change ujoint

The u joints are different and requires a Precision #447 from Napa.

The driveshaft may be too long now even with the lift and longer rear control arms.

The 06+ axles have abs sensors in the axle tubes which you don't need.

i think roadie is alluding to the fact that you will need to regear the front diff as well

 

[The_Roadie]

i think roadie is alluding to the fact that you will need to regear the front diff as well

Yep. I was a bit too subtle. 4.10 fronts are expensive and hard to find used because of the rarity. But you can regear them.

 

[jimmyjam]

Yep. I was a bit too subtle. 4.10 fronts are expensive and hard to find used because of the rarity. But you can regear them.

I'd think half the cost of regearing it would the labor to remove and replace the thing

any difference with between the I6 and V8 front diffs? I've got mine hanging on my oil pan doing nothing, if I ever get motivated to pull it would it work for an I6 guy?
if so, ssowners would be a good source for them as plenty of people like me have AWD->RWD swap parts laying around

 

[The_Roadie]

All front diffs are the same for all years, all models except for the three choices of gear ratio. Great idea about mining SSOwners for castoffs. There was an early design idea by GM to have a different number of mounting bolts, and you'll sometimes see aftermarket parts listings for a choice of bolt numbers, but it's a bogus question. Comes from the same data base error that causes parts shops to ask if you have a 140A or a 150A alternator when they sell you a serpentine belt. They're all 150A, but the parts store clerks don't know the right question to ask that determines the belt length is: "Do you have an EXT or a SWB?"

 

[gmcman]

I swapped mine and I want to strongly suggest that you make sure the axles are straight. When I say straight, go out there with some way of firmly mounting a dial gauge to check the flange for runout. Check up and down and lateral, reason I say this is these axles are under the SS for a reason, and when some get wrecked you don't know how it was wrecked.

I want to stress this since I have been through it, axles are only avail from the dealer, no aftermarket yet. I keep seeing the Dorman axles but I'm almost positive they are not avail for the SS yet. Once the axles are damaged, you will need new bearings and seals for whichever axle you replace.

There is an inherent whine on some axles under decal and this is hit or miss, GM repaired or swapped many rears because of this. Sometimes the "LS" fluid cured the noise but if the gears are worn then no fluid will change it.

Mine only has a faint whine but barely noticeable. Once I get around to it, the Eaton Tru-Trac is going in and if you have the $$$ I would do this anyway from the start.

Other than that, it's a direct swap, getting to a couple of the control arm bolts is a pain but no big deal. Driveshaft was shortened 1.5" and uses a "universal" joint for the large rear to the smaller rear, one half is larger. Make sure you take it to a competent driveline shop to get it balanced, must be rebalanced.

Not sure what's involved with speedo calibration but I think the reluctor wheel in the trans is changed for the 4:10 ratio.

 

[EXT Blazing]

hey thanks for he all the help guys, i'm going to still keep 3.42 gear ratio since i see they can be bought pretty cheap plus i like the highway mileage i get with them, thanks for the heads up i never even thought about checking the axles i was just gonna take off the diff cover and check for wear.

 

[gmcman]

I just realized you have the EXT version.... Not sure on driveshaft length, but I would guess it still needs to be altered 1.5". I don't know if 3.42 is avail for the 9.5" semi-float rear, be sure to check.

 

[EXT Blazing]

Yup I have the ext, the 3.42 gears are available for it a lot people on the tbss do them, right now im trying to look for pictures in difference driveshafts. I found a local driveshaft shop that builds repairs and balance them. They do semis mostly but said a car or truck isn't a problem.