BOP or Buick Posi Unit 8.2?

Johnny406
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BOP or Buick Posi Unit 8.2?

Postby Johnny406 » Fri Jan 29, 2016 12:34 pm

Hi Jim, I have what I believe is a BOP 8.2 posi but a search I did on the 620899 "indicates" that it is a Buick. But, both carrier bearings are the same size. The carrier says ISSUED 5-30-61; US Patent 2821088; CAN Patent 620899. Can you shed some light on what it actually is?

Thank you,
John
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monzaz
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Re: BOP or Buick Posi Unit 8.2?

Postby monzaz » Sun Jan 31, 2016 10:06 am

The only way you can ID these units is physical measuring. No Numbers work.

So if the unit has 3/8 bolt holes your in the 8.2 world (usually)
If the unit has 7/16 ring gear bolt holes it will be a 8.5.

Borg Warner unit (which is what this is) cone style posi....


Next we need to see what the ring gear machine land distance is. (reference the attach picture how to measure)
This will tell us what series and also what the unit is in rear type.

Axle spline will help but you can also check the side gear for a c-clip pocket (a recessed cut back in the side gear where the c-clip will ride when a c-clip axle is installed)
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monzaz
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Re: BOP or Buick Posi Unit 8.2?

Postby monzaz » Sun Jan 31, 2016 10:07 am

Just from the looks of the picture I would say this is a 10 bolt 8.5 and a 3 series ...THAT IS A GUESS. holes appear to be big 7/16" and ring gear land is way to the driver side. Will see once you get me all the info.
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Johnny406
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Re: BOP or Buick Posi Unit 8.2?

Postby Johnny406 » Thu Feb 11, 2016 12:11 pm

Hi Jim,

Thanks for the idea, it took awhile but I finally found the original 8.5 carrier from my 81 T/A for a side by side comparison. The posi unit has smaller holes. For giggles I stuck the Richmond 3.90 ring on it and it lines up perfectly as the ring has the smaller holes as well.
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monzaz
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Re: BOP or Buick Posi Unit 8.2?

Postby monzaz » Thu Feb 11, 2016 6:07 pm

10 bolt 8.2 chevy probably a series three carrier...Your picture is at too much of an angle to get a proper measurement BUT from the difference in the carriers i am sure that it is a CHEVY 10 bolt 8.2 1964-1972 rears it can be used in and the 3.08 -4.56 ratio. 3/8" holes are the give away...It is a Borg warner unit and is a CONE type unit. Jim
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