new kid. Axle code questions, G80 diff?

[stomp13]

Hello all,

First off, great site. I used the search for "axle code" and didnt come up with anything but.....

My dad just give me his very nice and top running 1999 Astro LT AWD. Where do I look to see what my stock gearing is and also to see if I have the G80 rear diff? What are the codes?

Second question: If I do have the G80, is it any good? I know of alot of stock diff that kind of suck.

third, I see that my rear is the corp 7.6inch, but when I look for gears (randys) they all show 7.5inch. Can 7.5s be used in the 7.6?

thank you (cool a smilie drinking Guinness!!!)

[ihatemybike]

If the sticker hasn't gone missing the RPO codes should be listed on the passenger side door.

G8? I think you mean G80. Several guys on the board have them and like them, others (myself included) want em. From what I've read the G80 is an Eaton limited slip differential and they do fine behind the 4.3L engine.

These vans do use the 7.5" rears. What is your basis for identifying it as a 7.6"?

[stomp13]

lol, yeah G80. sorry.

Randys ring and pinion show that 98 and up Astro use 7.6inch rear. But if 7.5inch gears work than I dont care what size it is.

[ihatemybike]

Might be a typo at Randy's. Check some other sites Jegs, Summit, etc for further verification.

[stomp13]

will do thanks. Yes the sticker is still on, its got 3.42s. Do you know the code for the G80? Please tell me its not G80 (duh)

[ihatemybike]

Please tell me its not G80 (duh)

OK, I won't. Think you know what that means though.

[stomp13]

crap
One last question about this. Ok so the code for the G80 is G80 but what gearing is it? Is that also shown as GU5, GU6, GT4 with G80 code?

Thank you for your help.

[ihatemybike]

Yup, you'll see a code for the gearing and a code for the G80.

[stomp13]

Thank you!

[LiftedAWDAstro]

The rear axle is in fact a GM 10 bolt 7.625" and is NOT a 7.5". It is 1/8" bigger! Randy's is correct. The 7.5" gear swap in with no problem and you can even use gears out of old S-10's. You can find 4.11's fairly cheap this way.

The front axle in all AWD's is a 7.25".

GU6 is 3.42's
GT4 is 3.73's
GT5 is 4.10's
G80 is the posi code

The G80 posi is decent posi. It holds up well to the 4.3 engine.

There is a list of RPO codes stickied in the "Technical" section.

[ihatemybike]

Dean is right, it's 7.625". Didn't have time to search earlier.

[Moreforles]

how do you know it was a guinness? there wasn't another smily next to him say "excellent"

I think it was Iced tea..... although it looks more like the oil I drained from my safari

[potskie]

Dean is right, it's 7.625". Didn't have time to search earlier.

Of course he is. Dean is like an Astro axle god. I'd almost bet money he made that post completely from memory.