Offroad Trailblazers and Envoys

Retrofit Differentials

G80, GU6, GT4, GT5, WTF? This section is for gearing and driveline stuff.

by CNCwell » Tue Dec 31, 2013 3:48 pm

My local hunting has not turned up any '05 G80/GT5 diffs. I have however found a few locally that range from '02-'04. I remember reading that '06 and newer will not direct bolt onto an '05 or older but will an '02-'04 diff bolt onto an '05?
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by Trail X » Tue Dec 31, 2013 5:19 pm

Any axle will work on 2002-2005.... but the 2006+ can only get 2006+ axles.
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by CNCwell » Tue Dec 31, 2013 5:40 pm

JamesDowning wrote:Any axle will work on 2002-2005.... but the 2006+ can only get 2006+ axles.


Awesome, thank you. Looks like I have a new project!
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by mikekey » Tue Dec 31, 2013 6:10 pm

JamesDowning wrote:Any axle will work on 2002-2005.... but the 2006+ can only get 2006+ axles.


Just for clarification for future searchers, the answer to that is because of the speed sensor for the ABS, correct? And it's not used on 2002-2005...
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by Moots1288 » Tue Dec 31, 2013 6:55 pm

mikekey wrote:
JamesDowning wrote:Any axle will work on 2002-2005.... but the 2006+ can only get 2006+ axles.


Just for clarification for future searchers, the answer to that is because of the speed sensor for the ABS, correct? And it's not used on 2002-2005...
02-05 is on the transfer case and 06+ is on the axle tube.
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by Shdwdrgn » Fri Jan 03, 2014 3:38 pm

Since the OP has 4WD, it should probably be mentioned that there are two different models of the 2002 FRONT diff... Early 2002's had a single bolt hole behind the drain plug, and everything newer had two holes. When I was searching for my GT5 front diff, I found quite a few with the single hole, but hardly any (within reasonable price) with the dual holes.

Also I believe that, except for the difference in the mounting holes, any year of front diff will fit? The one I finally ended up with for my 2004TB came from a 2007SS and dropped right in place.

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by Trail X » Fri Jan 03, 2014 4:54 pm

For some reason I've thought I've heard someone say that the two mounting hole thing was never actually an issue.
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by Shdwdrgn » Fri Jan 03, 2014 5:08 pm

That wouldn't surprise me... I'd have to look at my truck to see which hole was actually used, and compare the position to a single-hole case though. Probably could have saved myself some money, but I was being picky and only looking at units with less than 100K miles on them.

Now if only I could sell the set with the 3.42 gears and get them out of my garage...
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by The Roadie » Fri Jan 03, 2014 5:27 pm

JamesDowning wrote:For some reason I've thought I've heard someone say that the two mounting hole thing was never actually an issue.
That was me. I thought all the ones in the field were the two-holers. Like the phantom 140A alternators that were never used in production.
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by djthumper » Fri Jan 03, 2014 5:27 pm

JamesDowning wrote:For some reason I've thought I've heard someone say that the two mounting hole thing was never actually an issue.

I believe that was Donny.
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by Shdwdrgn » Fri Jan 03, 2014 7:45 pm

The Roadie wrote:
JamesDowning wrote:For some reason I've thought I've heard someone say that the two mounting hole thing was never actually an issue.
That was me. I thought all the ones in the field were the two-holers. Like the phantom 140A alternators that were never used in production.


I've seen pictures on ebay of pulled diffs that have the single hole, so at least *some* of them made it to the field.
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by Aries » Fri Jan 03, 2014 8:51 pm

Shdwdrgn wrote:
The Roadie wrote:
JamesDowning wrote:For some reason I've thought I've heard someone say that the two mounting hole thing was never actually an issue.
That was me. I thought all the ones in the field were the two-holers. Like the phantom 140A alternators that were never used in production.


I've seen pictures on ebay of pulled diffs that have the single hole, so at least *some* of them made it to the field.

The front dif on my 02 TB EXT has one hole aft of the drain plug, Same as the one sitting on my work bench I got from an 02 TB that I'll re-gear
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by Trail X » Sat Jan 04, 2014 12:26 pm

From what I can tell, that's the same hole that the later year diffs use. I'm wondering if they just use that second hole as an install guide or something on the later years.
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by Conner299 » Sat Jan 04, 2014 12:48 pm

After checking the front diff, I just bought, I have a single hole as well. The area, where the second hole would be on mine, is quite thin. I'd say no more than 3/8". The area where the mounting hole is more along the lines of about 3/4", or more. Can't say for sure, as it is still at work. Unless someone does it before me, I'll get some pics up Monday. My guess is that second hole would be an install guide, or something else. Couldn't really see it being a mounting hole, with as thin as it is.

Edit: Forget what I said... Just relooked at the photo with two holes. I was thinking it was in the area, right below the second hole.
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by Aries » Sat Jan 04, 2014 4:10 pm

Conner299 wrote: My guess is that second hole would be an install guide.

In aviation we would refer to a hole that didn't get a bolt, screw or rivet as "Placed for tooling". It was a BS term we used rather then explaining that we didn't know what it was for or why it was there! :lol: It looked good in the report and was never questioned.
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by The Roadie » Sat Jan 04, 2014 5:38 pm

Aries wrote:.."Placed for tooling". ...
Oh, man. You have me rolling around considering how to use that phrase. In software reviews, in case the reviewer finds a function with no links elsewhere (orphan code we forgot to delete), we call it a "diagnostic stub". In hardware circuit design, we sometimes leave orphan circuits laying around (because components are so cheap nowadays) and not connected, in case we find we goofed a year later and need to wire those circuits in for a change order rework. Those are "for future feature expansion" or "for enhanced manufacturing test fault coverage". :lurk:
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