Chevy & GMC Vans

Does anyone know what kind of differential the 1991 Safari AWD has. I just got a repair manual for it but it doesn't have any information on all wheel drive components. Does it come with a limited slip?

They are all GM 10 bolt, but not the 8.5 inch ten bolt, its the smaller 7.xx something size.
you could look up the RPO codes on a white sticker on the glove box door.
Theres a lot of alphanumeric codes on it, and 2 of them should start with the letter "G".
G codes are about the axle. If your says G80, you have a limited slip axle.
The other G code tells the ratio. Eg. GT4 is a 3.73 maybe, my memory isnt so great anymore.

They are all GM 10 bolt, but not the 8.5 inch ten bolt, its the smaller 7.xx something size.
you could look up the RPO codes on a white sticker on the glove box door.
Theres a lot of alphanumeric codes on it, and 2 of them should start with the letter "G".
G codes are about the axle. If your says G80, you have a limited slip axle.

Thanks for the info. BTW, I have seen your youtube videos- great stuff. You are an inspiration to guys like me just starting out on the customization journey. I have never worked on vehicles before, but now I got the itch.

I looked at the codes and can see that I don't have the g80. I guess I have an open differential. I notice on internet car forums, people will talk about LSDs for rear rear drive trucks and 4x4s, but are LSDs used on AWD vehicles also? I mainly want my AWD to make my van into an awesome snow machine. Will a Limited Slip Differential help or hinder this goal. I have heard some say that posi-traction makes their vehicle slip more in snow/ice.

Can you get a compatible lsd out of a jimmy/blazer?

S10 Jimmy axles (rear) wont fit in a stro. but theres lottsa safastro axles out there.
The actual guts of the diff will swap between astro & S10, but not the axle housing itself.
The astro engine & Diff are offset a few inches to the right of center.

in an AWD van, the G80 will help on snow, and was OEM option.
My awd was 3.73 w/G80 and it was awesome in snow with BFG AT tires on it.
I might miss the AWD now that I have changed it to an np231 transfer case, but they both have their advantages.
I'm wanting now to convert my safari GT to AWD w/5 speed. As soon as the boat project is done....

It's a 7.6" ring gear, and yes there are several traction aids you can put in there, and they work great with AWD and in snow (you would have to lose traction in both rear wheels and one front to get stuck). You could get a G80 from other GM vehicles. There are also aftermarket ones such as the Powertrax lock-right or I really like torsen systems like Detroit Truetrac.

timelessbeing wrote:It's a 7.6" ring gear

Hey TB,
I haven't really seriously looked into it , but I've read it on these sites somewhere...

Is it true that there are actually 2 different sized astro ring gears?
A real early smaller version, and the newer larger version.
Newer being somewhere after the late 80s, early 90s
Both are 7.xx something. Neither is an 8.5" 10 bolt.

Yes. From '82-'88 it was 7.5"

gmcsasquatch wrote:I have heard some say that posi-traction makes their vehicle slip more in snow/ice.

Maybe they were talking about "lockers". These are differentials that are selectively activated by the driver by means cable, compressed air, electric actuator, hydraulic etc. and the lock the rear wheels together, preventing the one-wheel spin that you get with an open differential. However, by doing this you also lose drivability since making a turn requires the wheels to turn at different(ial) speeds. This is generally undesirable when driving through snow on-road. Since front and rear wheels also need to differentiate, the same can be said for transfer cases that lock together the front and rear driveshafts.

timelessbeing wrote:Yes. From '82-'88 it was 7.5"

Cool, Thanks,

I wonder if gear sets, carriers & housings are interchangeable between the 7.5 & 7.6?
I guess I have 1 of those 7.5" with 3.08 open gears and 3 more 7.6's. (2x 3.73/G80, & 1, 3.42/open)

I wish I could find a true list of the gear ratios available and actually could be found, for front axles.
If I convert my GT to AWD, I would like to run 3.08 G80 gears with the 5 speed.

How likely is it to find a stock 3.08 front axle?

Thanks guys for the replies, I really appreciate it. Looking forward to modding my astro!

The M/L vans used the GM 10 bolt axle in all years for the rear end. 1985 to 1989 were 7.5 ring gear diameter and 26 spline axles. 1990 went to 7.625" ring gear and 28 spline axles. The ring/pinion combos swap between the carriers and were also used in S-10/S-15 trucks and Blazers/Jimmy's. The carrier break is 3.08/3.23.

The front axle is the IFS 7.25" and is the same ring and pinion as the s-10's. These are all reverse cut. The carrier break is again 3.08/3.23.

Thanks Lifted.

This is why they pay him the big bucks.

LiftedAWDAstro wrote:The carrier break is 3.08/3.23.
The front axle is the IFS 7.25" and is the same ring and pinion as the s-10's. These are all reverse cut. The carrier break is again 3.08/3.23.

Thanks Lifted!
can you please tell me what 'the carrier break'' means? I'm blonde and new at diffs...

I have a 7.625 ring on a G80. Its a 3.73:1
Can I bolt my 1987 7.5 ring - 3.08 gears to that newer G80 carrier which has the 3.73?

I'm grasping at straws, but I think he means the carriers can only accomodate certain size ring gears. Since you want to go two sizes smaller, it may not match.