Need help to Identify the front differential plz

[Arctic-Rodz]

On my 1998 yukon.
I ordered a set of 4.10 gears from Summit and instead they shipped 4.11's with an install kit that was for up to 1971 GM trucks. So I call back and they ask what size the diff was on the front. ( and thats cause I spoke to a sales rep when i ordered the gears) The rep said having 4.11's on the front and 4.10's in the back wouldnt matter but I told him 4.10's, he didnt say he was placing the 4.11's on order.

Customer service asked if it was either an 8.2" or 8.25" front IRS diff. I thought there was only an 8.2 for the front? I called the GM Dealership and they didnt know, all they could tell me is that it comes with 3.73 gears stock.

Anyone know what size the diff is or how to find out?

Thanks

 

[haks310]

If it was 3.73s stock then it is the 8.25

 

[bai78]

If it was 3.73s stock then it is the 8.25

^^^ 8.25 IFS as stated above.

 

[Arctic-Rodz]

yes, IFS i put IRS....
So 8.25" for sure?
The guy i spoke to on the phone @ summit when i ordered the gears said it was 8.2"
and when i called back, the other guy didnt know. Said they offered 8.2" and 8.25"

So if it carried under a 3.73 its a 8.2"?

 

[bai78]

It doesn't really matter what gears they came equipped with, 3.42 (like mine), 3.73, or even 4.10's. Our GMT400 trucks have the 8.25 IFS. IIRC, only the 1 tons would have the 9.25 IFS front diff.

Aren't the 8.2's for front solid axles? That's pretty much what they had pre '88/IFS correct?

 

[Arctic-Rodz]

I dont know, the person at summit asked if it was 8.2 or 8.25 IFS. So the 8.2? what did that come out on? And for sure its not for mine then....