8.2 or 8.5?

It’s been several years since i’ve had a v8 buick but for a while now I’ve had this thing in my head for making a high hp sleeper out of a mid-80’s leSabere coupe, and when a super clean low miles example came along, I just had to pull the trigger.

As I am looking it over and making my plans, I am expecting it to have the smaller 7.5 rear but I an not too sure. It has what looks to me to be an 8.5 based upon the online ID guides. It also has a tag the reads “use only limited slip oil” which sounds like a positive sign to me.

Can someone on here help me positively ID this sucker?

Thanks in advance - Rich

 

Perhaps some photos would help

 

Looks like a very clean 8.5”.
A 7.5” cover is distinctively different.

 

Thanks Brian. I’ve been going through and decoding some of the RPO codes from the sticker in the trunk and although I thought all mid-80s big cars came with the 8.2, I suppose the 8.5 was an option for the leSabre in 1985.

I guess I lucked out since this one seems to have:
G87 - 8.5 inch,
G-80 - limited slip, and
GU2- 2.73 ratio

 

I agree, looks like a 8.5
here is a source I use, frequently, LOL

https://www.chevydiy.com/history-and-identification-of-chevy-10-and-12-bolt-chevy-differentials/

 

Got to ask. What makes the 8.2 Buick used in the 68 to 70 GS so much better that TA performance claims in it's catalogs? I read about the bolt sizes and pinion bearing size comparisons but is it that stouter compared to the 8.2's in the GTO's, 442's?

 

The other BOP 8.2’s are actually very similar to the Chevy 8.2”. The Buick 8.2” is definitely above all of them.

 

Question? Why are you comparing 8.2 to a 8.5... there is no comparison... 8.5 corp is the best 10 bolt rear in GMs arsenal. THAT is why it is still being used today in trucks and SUV etc. it is called the 8.625 now and has been upgraded with larger carrier bearings and even pinion bearings have been changed in some also. (really odd ball pinion bearings that are only made by KOYO. JAPAN. Nice huh...

Remember everyone is trying to sell parts. So they gave good reasons to use this rear over all other 10 bolt rears and it was a good rear and still will do the job no doubt.
8.5 pinion is slightly longer and thicker at the yoke spline 30 spline to the 8.25 27 spline. Pinion bearing is lager diameter in the 8.25 BUT it is also not as tall is been problematic in the dodge trucks 9.25 which uses the same size pinion inner bearing...they wipe out all the time in dodge 9.25... we do LOTS of these bearing rebuilds.

so we can go back and forth showing good and bad on all rears. But if you buy good parts and build it right - all rears will do the job very well on the street for sure and even some track time. Size is still up to the customer as to what they think they will need in heavy duty rear size .... so there are some other thoughts for you to go through also.

I personally think the 8.5 rear under the LeSabre is great and will work great. IF you want to up grade it to be stronger do the 30 spline posi and 30 spline axles... BUT since you already have the LSD in there cost effective would be to install gears and seals at a minimum and have some fun!

Jim J D Race

 

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