# Help Identifying rear Dif



## Billt102 (Feb 6, 2020)

I found this rear end for sale local. The guy had it explained as a "67 chevelle 8.2 posi rear". says it is 8.2 ring, 3.55 gears and internals are tight.
Looks like a BOP to me, but I am no expert. I want to replace my 3.08 one legger in my '67 Tempest with this.
Oh, and he added that it is 54" from backer plate to backer plate.
Can someone look at these pics and tell me what I am looking at, and if it should swap into my 67 tempest without modification? He's asking $800 for it which seems reasonable to me.


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## Drewm (Jul 27, 2021)

Certainly looks like a BOP rear. I think 54 (or 54 1/2) would make it an earlier rear, 64 or 65. At some point on the 66's they went to a wider rear, by one inch, which is only 1/2 inch per side Either rear should fit on your car with no problems. I would be concerned buying an unknown rear for that amount. There should be a date code and casting number on the center section somewhere. On my old 8.2 rear, I think it was on the lower left casting web. Also can look at how the axles are retained. Chevy uses C-clips, and BOP did not. 

Regardless, I would be leary of buying a rear of unknown history. Posi units wear out and some are not rebuildable. Easy enough to get a new posi unit and install yourself if you are so inclined. For reference, I just sold my 8.2 rear with posi and 3.55 gears for $200 bucks. That one looks to be in better shape than mine was, but I replaced it with a 8.5 rear from a 71 olds. Much stronger and gears and carriers are readily available. There are also plenty of aftermarket builders depending on how much you want to spend. I spent about $1200 for the 8.5 rear, gears, and posi carrier and put it together myself, so I have a completely rebuilt rear for a good amount less than an aftermarket rear.

But, depending on what kind of use the rear will see, this one may be perfectly adequate and give you years of excellent service. Hopefully that helps.


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## Billt102 (Feb 6, 2020)

Thanks Drewm. Those echo some of my thoughts as well. . info I had seen was that 54 +/- indicated an earlier BOP, narrower than the 55 1/2 that is on it. I looked at 9" FORD A-body conversions, they aren't THAT much more. keep thinking maybe just leave the 3.08 1-legger in it, its not a bad gear for cruising around with the TH 400. but I want to get rid of my 670 heads and if I go aluminum, i'm going to change the cam and intake and with more HP, I'm going to want posi... I need to quit being so dang wishy-washy.


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## armyadarkness (Dec 7, 2020)

If you want to put an Auburn posi and some new gears in your car, you can do it for the same money, maybe less!


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## Mine'sa66 (Oct 30, 2019)

These guys are great for rears. Bought my custom 12 bolt from them... JDrace.com


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## Billt102 (Feb 6, 2020)

armyadarkness said:


> If you want to put an Auburn posi and some new gears in your car, you can do it for the same money, maybe less!


Yes, if I want to stay at 3.08 I can do that. Can't find 3.23 gears and the big carrier would give me more options. Thanks.


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## armyadarkness (Dec 7, 2020)

Billt102 said:


> Yes, if I want to stay at 3.08 I can do that. Can't find 3.23 gears and the big carrier would give me more options. Thanks.


If you change carriers/ ie install a new Auburn, you can have whatever gears you like!


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## armyadarkness (Dec 7, 2020)

You can either buy a 3.36 and up diff, or a 3.23 and down. Either will fit in any BOP diff housing.



https://www.opgi.com/drivetrain/differential-rear-end-components/grip-n-loc-differential5/g242495.html


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## armyadarkness (Dec 7, 2020)

Cheaper at Summit








Auburn Gear Inc 546060 Auburn Gear Grip-N-Loc Differentials | Summit Racing


Free Shipping - Auburn Gear Grip-N-Loc Differentials with qualifying orders of $99. Shop Differential Carriers at Summit Racing.




www.summitracing.com


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## Billt102 (Feb 6, 2020)

armyadarkness said:


> You can either buy a 3.36 and up diff, or a 3.23 and down. Either will fit in any BOP diff housing.
> 
> 
> 
> https://www.opgi.com/drivetrain/differential-rear-end-components/grip-n-loc-differential5/g242495.html


I guess I misunderstood that 3.36 and up required a different housing... So I can use my entire housing and axles and change ring and pinion and carrier? I know you post on this topic a lot Army and that you have done a number of these, I just thought I was stuck with replacing the whole deal if I wanted to go to a 3.36 or 3.55 etc..
Bill


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## armyadarkness (Dec 7, 2020)

Billt102 said:


> I guess I misunderstood that 3.36 and up required a different housing... So I can use my entire housing and axles and change ring and pinion and carrier?


YES!!!!


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## armyadarkness (Dec 7, 2020)

Billt102 said:


> I guess I misunderstood that 3.36 and up required a different housing... So I can use my entire housing and axles and change ring and pinion and carrier? I know you post on this topic a lot Army and that you have done a number of these, I just thought I was stuck with replacing the whole deal if I wanted to go to a 3.36 or 3.55 etc..
> Bill


Nope. You're good to go! PM me if you need any guidance.


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## coyote595 (Dec 4, 2019)

3.36 and up requires the proper gear carrier. The housing does not change.


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