Is it possible to get a Posi for a 2.78 8.2 BOP for a 69 firebird? I'm thinking about removing my 3.42 posi and putting the 2.78 back in, and it would be nice to have a posi.

Yes, you can get a posi carrier that will accept 2.78 gears. I recommend an aftermarket carrier from JEGS or SUMMIT.
Jim

Dave, I have a what I believe are 2.76 gears, and it's a posi unit... But Mine is out of a 79 TA for the rear disc... and that would be the 8.5 I believe...

But yes, also check with Randy's Ring and Pinion as they are one of the clubs (Western Washington Firebirds) sponsors for our show each year... mention the club, and perhaps you can get some kind of discount?

Also David Morton just in Redmond, had his rear end work done at a shop in Totem Lake, and said they did a great job for a great price. Maybe email him for info if you still have his email addy? If not let me know and I'll send it to you!

Brett - 67 Drop Top 455!
[email protected]

I'm not sure who makes an aftermarket posi for a 2:78. Auburn makes one for 2:93 - 3:23 and 3:36 and up 8.2 BOP. Eaton makes one for 3:36 and up 8.2 BOP. You might need to find a good used one and have it rebuilt.

do you know how to weld???
do you know where those spider gears are?....well all you need to do is....


what??? it was just a thought...geeeez

welding sounds cheapest and most effective!

Thanks for all the great info. I thought all aftermarket was for 3 series BOP, i.e. 3.36 and up. If Auburn makes one for a 2.93, then it must work for the 2.78 also. I think it's the same carrier until you get down to a 2.54. That's nice to know.

Brett, yeah I still have Dave's email addy. Thanks for all the info on local businesses.
That 79 T/A 8.5 is an excellent unit. you might wanna hold onto that one!

I'm just fishing for ideas right now, cause I'm kinda low on "Green Quarters" if you'all know what I mean! The bird just sits in the garage and I havn't spent a dime on it lately.

If I could score a driveshaft that would bolt right in I would install the 2.78 again for sure. Then I could swap them back and forth.

Someday when money is once again flowing free I'll put in a tranny with an overdrive and use the 3.42 Posi.

I was looking into this the other day. Auburn seems to offer a limited slip unit for BOP applications in the 8.2 10 bolt.

http://www.auburngear.com/aftermarket/products/differentials/default.asp?page=ps

Does anyone have experience with this unit or the original safety track differential? It is a cone clutch type. Is the 8.2 rear durable enough to stand up to an "enhanced" 400 engine?

Freydog69,

I've got a driveshaft for a TH400 if you need one, not sure on your tranny though.

I have read that the BOP 8.2 is very durable and can stand up to an "enhanced" 400. It has beefy axles that bolt in, therefore no "C" clips. Plus it has stonger U-joint straps. It's better than a chevy 8.2, but not as strong as the 8.5 10 bolt.

thanks for the link firebird red. After looking at the link, I'm not so sure the Auburn Posi will work with a 2.78. 2.93 must really be the cutoff, like steve G was saying.

thanks trauschu, I'll try to find out if it will fit my TH350, and how much shipping is.

I could always have my driveshaft lengthened, replace the u-joint, and balance it for about 200 bucks, maybe less.