'03 Trailblazer complete rear axle replacement stuck mid swap, need help ASAP!!!!

[NaGall]

I need help! I'm stalled out literally at the half way point. To sum up my predicament, my rear differential literally exploded and blew a hole through the bottom of my axle back in December 2022. The garage that replaced the axle assembly screwed me over with a salvage yard axle. The factors leading to this second failure are: not enough gear oil in the diff cover, the wrong differential, the wrong gear ratio, not 4WD compatible, not ABS compatible, seized/stuck parking brake assembly. After 8 months thinking all was right with my little red Chevy, that axle failed (obviously).

Now to where I have found myself tonight. I've successfully removed and disconnected everything from the bad axle and the axle is supported with jack stands, as is the drive shaft. I have removed the u-brackets from the axle/drive shaft joint, but I can't dislodge the drive shaft from the rear axle. I am hoping someone reads this and can direct me on what I should do next, otherwise I am going to start beating the hell out of that joint with a pry bar and a 5-lb mallet. Oh, yeah, during the process of disconnecting everything from the failed axle, my phone was destroyed after the passenger coil spring fell on it, so I'm double f'ed at the moment.

Please help..........

 

[TollKeeper]

get behind the U-Joint with a large screwdriver or pry bar. It will pop out. Make sure the drive shaft is supported by your hand when you do this, otherwise that driveshaft will hit the floor, and the u-joint will explode! (not literally, but the caps will fall off, and the needle bearings will go everywhere).

I went thru 5 u-joints in the last year...

For your replacement axle, have you determined what your axle ratio is? GU6, GT4, GT5?

Do you have/want the locker axle, other wise known as a G80?

Can you tell us more about your truck? Year, Model, long or short wheel base, engine?

As for telling what gear axle you have, you just need to look in your glove box, there will be a sticker in there telling you all your build codes.. Look for the 3 digit codes I mentioned above.

GU6 - 3.42
GT4 - 3.73
GT5 - 4.11
G80 - Eaton Auto Locking Differential.

Long/short wheel base is important, as is knowing your engine, because it can change the type of differential you have, from the 8.0 to a 8.6. If replacing, its always best, regardless of what you have currently, to replace it with a 8.6. The 8.6 is stronger, and can take a bit more abuse. The 8.6 can be found in all Long Wheel Bases, and all short wheel bases with a V8.. With the one exception being the Trailblazer SS and the Saab 9-7x Aero. Thats a Completely different axle. The year is also important as the 2002-2004 WILL NOT work in the 2005-2009. But the 2005-2009 WILL work in the 2002-2004.

 

[TollKeeper]

P.S. There is no such thing as not 4wd compatible. A rear axle is a rear axle.
P.S.S. The 8.0 to 8.6 will bolt in directly. Nothing changed other than the manufacturing process.

 

[NaGall]

Here is the update. I had to order a replacement axle assembly (complete build) through O'Reilly Auto from Power Torque. They really pulled this one out for me. I ordered one axle, only to have it arrive and discover that it was not the correct gear ratio. My RPO codes are G80 and GT4. As soon as we discovered that, the O'Reilly manager called Power Torque directly and they were able to place a custom order for me on the spot, without any increase in price or additional cost. That took care of the axle.

My Trailblazer is a 2003, LTZ, with the standard 5 passenger short wheel base, and it's running with the 4.2 I6 engine. I have installed a suspension lift, 2.5 inch on the front and 2 inch on the rear. I've upgraded the shocks to Bilstein B8-5100 adjustables up front and Fox 2.0 Nitro's on the rear. I replaced the stock coils on the rear with a set of new coils from a 2004 Tahoe Z71 (thats where the 2 inches come from) and new coils on the front struts. I've replaced both front cv axles, and hubs, as well as both front rotors within the past 6 months.

When my first axle failed, the garage that swapped it out removed and kept my new EBC brake kits from the rear, along with the new parking brake assemblies. They charged me for a reman axle, only for me to find it was a salvage yard rescue from some local pick and pull operation. The replacement axle still had the purchase paint pen scribbles in yellow on the axle shaft housing. I confirmed this crap axle is a 3.42:1 which I hope didn't destroy my 4WD components. I have yet to tear into that little nugget. I just finished the install of the new axle, have been running around town (nothing hard core or extended yet) and so far this axle feels and drives like butter melting on a mirror. I hope this helps. Thanks for all the help so far. Glad I found this site.