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1997 GMC Safari SLX - AWD
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Discussion Starter · #1 ·
I have seen a few posts about this, but most were asking about RWD and not many things in the threads were concise or answered.

My situation:

I own a 1997 GMC Safari AWD, 5 Lug, 3.42 gears

I stumbled upon a 2005 AWD Astro at the junkyard - I haven't checked yet, BUT assuming it has the 3.73 gears I want (since it seems to have a tow package), I want to know....

How difficult would it be to swap in ALL the 6 lug bits, onto my 1997 5 Lug AWD. (Let's ignore the part about 16" wheels being the minimum etc)

Does the front Diff bolt right in?
Does the rear axle bolt right in?
Do the front spindles and brakes bolt right in?
Would the driveshafts need to be different (since I have the Borg Warner T-case, the 2005 is New venture) ?
Would the front CV's stay mine, or do I need the donor ones off the 2005?

It seems like a TON of work, but man, having discs out rear, dual piston front calipers AND 3.73 gears would be sweet.

HOWEVER if it's impossible or a SH** TON of fab work and fiddling, probably not worth it for me. (I can wait for a 1990s 3.73 equipped van to show up)

But was curious if anyone's done it !
 

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01 Astro RWD Cargo, 97 AWD Mark III
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You will need the front 6 bolt hubs with spindles, and CV shafts, and the complete rear axle. Along with the complete 03-05 brake system (master cylinder, proportioning valve, ABS, calipers, and new lines). Not sure how compatible the brake electronics are.
 

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05 Astro AWD
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But don’t bet that it has 3.73 gears. My ‘05 AWD with tow package has 3.42. In fact, the only Astro/Safari I have that does have 3.73 is my ‘93 AWD (and my ‘93 Bravada).
 

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01 Astro RWD Cargo, 97 AWD Mark III
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The cv shafts should be interchangeable since the transfer case is the same.
The CV shafts for the 6 lug are 23 15/32", 5 Lug are 22 1/4"
The difference is because of the spindles
 

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1997 GMC Safari SLX - AWD
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Discussion Starter · #7 ·
Hey folks! Well I went to the wrecker..... GT4 G80 RPO sticker on the AWD 2005........ I am very tempted to swap it all haha. However, I think it would be way more work than I want. Having to figure out the ABS and all the crap wiring differences, seems daunting. I'd need the axle out rear complete, front CV's, front spindles and brakes, probably some bits and pieces here and there.

Not sure, I think it may be wiser for me to just wait for a 5 Lug 3.73 AWD to show up one day, and grab those bits, would be easier to swap over and less hassle.

Still.... it has the gears and a rear posi... that's tempting... ;)
 

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1998 LS AWD Forest Green metallic
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964 Posts
OR....Just carry the two different spare wheels, and hope the diameters are equal ( not just 'close')
An impractical idea...but you would have the disc brake rear end G80 .. of course the brake plumbing and all might still be 'interesting'.
Yeah, it seem to be a lot of work for not much real gain.
 

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01 Astro RWD Cargo, 97 AWD Mark III
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Still.... it has the gears and a rear posi... that's tempting... ;)
If you do give in to temptation, Let me know.
There are a few parking brake cable brackets that I need.

It would also be good for a set of torsion bars.
 

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2000 Lifted 4x4 Astro 92 V8-350 Shorty
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I'm in the same situation.. I have access to nice 6-lug differentials with 3.73 gears, but all my vans are 5-lug. I have NO desire to switch to 6-lug (requiring new wheels & tires) or run mixed configurations..

What would be nice would be if I could switch the rear, then swap back in the 5-lug axles into the 6 lug differential. Problem would be simply solved.
 

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1997 GMC Safari SLX - AWD
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Discussion Starter · #12 ·
I'm in the same situation.. I have access to nice 6-lug differentials with 3.73 gears, but all my vans are 5-lug. I have NO desire to switch to 6-lug (requiring new wheels & tires) or run mixed configurations..

What would be nice would be if I could switch the rear, then swap back in the 5-lug axles into the 6 lug differential. Problem would be simply solved.
I was wondering if I could slide in the 5 Lug drum brakes and axle shafts into the 6 Lug rear axle assembly, not sure on the compatibility. Is the Front differential IDENTICAL to the 5 lug, as it sits on the 6 lug? Because then that would be the easy part of the swap, just the front Diff. The rear is the dilemma
 

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01 Astro RWD Cargo, 97 AWD Mark III
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I was wondering if I could slide in the 5 Lug drum brakes and axle shafts into the 6 Lug rear axle assembly, not sure on the compatibility.
Not possible. The 6 lug 03-05 axle is 31mm wider on each side.
You could get new 5 lug axle shafts made to the 6 lug length, but it does not make sense to degrade back to drum brakes. The 5 lug drum backing plate will not bolt up to the 6 lug axle.

Is the Front differential IDENTICAL to the 5 lug, as it sits on the 6 lug? Because then that would be the easy part of the swap, just the front Diff. The rear is the dilemma
As far as the 97-05 the front differential is the same.
The 90-96 was different in that it used the flanged style output.

You could always take the carrier and gears from the 6 lug and swap them into the 5 lug, or just pick up a 98-02 Camaro Zexel Torsen Carrier and a 3.73 gearset
 

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01 Astro RWD Cargo, 97 AWD Mark III
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Can the hub flanges just get redrilled and move the lug studs?
It could be done but trying to match the rear disc brake up to the 5 lug is another Pandora's box!
No matching rotors.
 

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2000 Lifted 4x4 Astro 92 V8-350 Shorty
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You could get new 5 lug axle shafts made to the 6 lug length, but it does not make sense to degrade back to drum brakes.
It makes a lot of sense if you consider the reasons I already gave.
 

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1997 GMC Safari SLX - AWD
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Discussion Starter · #16 ·
You could always take the carrier and gears from the 6 lug and swap them into the 5 lug, or just pick up a 98-02 Camaro Zexel Torsen Carrier and a 3.73 gearset
Well hold up now....Now we're talking. So I could gut the diffs, along with the pinion gear, and that would all fit directly into my '97 5-lug's pumpkins? That would be stellar!
 

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1998 LS AWD Forest Green metallic
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Well hold up now....Now we're talking. So I could gut the diffs, along with the pinion gear, and that would all fit directly into my '97 5-lug's pumpkins? That would be stellar!
I did essentially that.
I bought a used (cleaned and inspected) Camaro/Firebird Torsen unit, and had a local shop install the Torsen L/S assembly using my existing ring and pinion . I just ( this week) had all the bearings replaced, re-shimed and new a crush sleeve and seals.
Rod J
Issaquah, WA
 

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01 Astro RWD Cargo, 97 AWD Mark III
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It makes a lot of sense if you consider the reasons I already gave.
I understand the desire to maintain the 5x5 bolt circle and serviceability
but
The brake incompatibility issue more than offsets any benefit from the wider axle.
As stated before the 5 lug drum brake will not swap to the wider 6 lug axle.
Not to mention the necessity of having to find 16" wheels to clear the disc brakes if you could find a compatible rotor.

It is simpler and far less hassle swapping the internals, or just get a new gearset.
 

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01 Astro RWD Cargo, 97 AWD Mark III
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Well hold up now....Now we're talking. So I could gut the diffs, along with the pinion gear, and that would all fit directly into my '97 5-lug's pumpkins? That would be stellar!
If what you are looking to achieve is a gear change from 3.42 to 3.73 it is a simple matter of replacing the gearset. It then makes sense to upgrade to the Torsen while you are at it. A gear change always requires resetting the backlash on the new gears.

I am not a fan of the G80 Gov-Loc LSD. It is a clutch based limited slip which means worn clutch plates and springs. A used Gov-Lov will require rebuilding prior to being installed. Even then they can and do fail.

If you break a Torsen. The vehicle will not be salvageable!
 
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