Identification of rear end - Impala Tech
Transmission & Driveline Transmissions & Differentials

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post #1 of 12 (permalink) Old 07-19-2020, 07:27 PM Thread Starter
 
 
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Identification of rear end

I know it’s a 10 bolt 8.2 or 8.5? What does the BB0723 stand for?
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post #2 of 12 (permalink) Old 07-19-2020, 08:13 PM
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Not an 8.5 ten bolt that wasn't produced before 1972.

That is a Salisbury style rear end (drop out center section like the 9 inch from Ford) that was used by Chevrolet. All of the other GM brands used a bigger stronger version of this rear end because they all had eight cylinder engines long before Chevrolet ever did. As such it is weak in comparison to any other rear end you will find designed for use behind the 85 horsepower 216 cubic inch six introduced just before WWII. It was carried over after the war through 1964 were it was replaced with a Spicer rear end purchased because the 348-409 and later 327 engines would break it with ease.

Unless there is the letter "P"cast into the case it is an open rear end. The limited slip differential was offered in the "P" case only and it will not fit inside an open case.

BB0723 is the casting number for that case. Every GM part has a unique number (the casting number differs from the part number) and is basically how they knew what mold to use to cast the part they wanted to make.

Big Dave
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post #3 of 12 (permalink) Old 07-19-2020, 09:30 PM Thread Starter
 
 
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Thanks Dave, I’m trying to keep the numbers matching on driveline, motor, and tranny in this 64. I pulled the 327 to rebuild this fall/winter and plan on pulling it up to 375-400hp. Do you think this rear end was stock? According to the date codes it looks like it, but it’s not gonna hold what I put to it...what rear end dit they use with a327 300hp or the 409?
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post #4 of 12 (permalink) Old 07-19-2020, 10:52 PM
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A whole bunch of what you have now. I used to carry a spare rear end, with me in the trunk when I had my 409 powered '53 Chevy. Would break one a week. I got very good at rebuilding them.

Finally found a '63 Olds in a junk yard and installed the Pontiac-Olds rear in place of the Chevy rear end and then I moved on to breaking T-10 four speeds.

Back when these cars were on the designing board the engineers designed them to meet 150% of the anticipated torque load. The rear end was designed for a 215 cube six, and was in dangerous territory with the 265 cube V8 introduced in 1955. The 283 from 1957 was pushing the upper limit of the design limit.

The 348 introduced in 1958 was breaking them all the time with a manual transmission. But customers didn't mind as warranty covered the repair cost for five years after date of purchase. Chevy minded because they were paying to fix them. The 327 made the scene in 1963 and was the coffin in that rear end as a 327 could also break it with ease.

Today every one has a SBC that can make 500 horse on the internet, not so much on the street; but they still make more power than a similar sized engine from the early sixties thanks to bigger heads and more modern cams. That and few run a 283 any more, most are 350's or 383 cube engines.

Big Dave
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post #5 of 12 (permalink) Old 07-19-2020, 11:40 PM
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BB is the Differential Code.

What you have is a Non-Posi 3.36 Rear made by the Buffalo plant.

Does the car have a 3-Speed Trans?

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post #6 of 12 (permalink) Old 07-19-2020, 11:59 PM
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Also, the 0723 is the Assembly Date (July 23rd).

If original to the car, it looks like you have a very late built '64.

By the way, this is the same type Rear even if it had a 409, although most 409's were ordered with a Posi Unit.

The Posi may have been mandatory with a 409 order, but I don't believe it was.

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post #7 of 12 (permalink) Old 07-20-2020, 12:35 AM Thread Starter
 
 
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Lol, I dropped a 383 in it for the time being. It’s pushing about 340hp. Guess I’m gonna be dropping more $’s for a rear end soon. Olds/ Pontiac are getting hard to find. Are there any others that would bolt up and Fit with welding a few brackets in the right place’s?
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post #8 of 12 (permalink) Old 07-20-2020, 12:38 AM Thread Starter
 
 
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62Bill it has a PG 3.36 seems to do ok with the spare th350 I put in it.
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post #9 of 12 (permalink) Old 07-20-2020, 12:42 AM Thread Starter
 
 
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I have all the #’s matching 327 and the power glide I’ve just pulled them and dropped a 383 and a th350 in until they are done this winter.
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post #10 of 12 (permalink) Old 07-20-2020, 07:53 AM
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A lot of it has to depend on traction. If your running standard bias ply street tires and not doing burn outs or neutral slams the stock rear end will hold up. You start putting slicks on the car and doing hard launches and say good by rear end. Also people like to put wide low profile tires on these cars and depending on tire compound and such you may have to be careful if your doing that. You can put a Posi in a standard case it just requires a little grinding on one of the gussets. They even make an aftermarket Posi that fits in the case if you can't find an original one. If your going racing with the car I would swap the rear out and while a lot of people swear by them I would avoid the BOP rear and go straight for a 12 bolt or 9" ford. If you ever plan to put down over 1000+ HP into slicks then you might want to go with a Dana 60, but these rear ends weigh a ton and you really don't need that kind of strength until you start getting into forced induction motors.
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post #11 of 12 (permalink) Old 07-20-2020, 08:56 AM
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Quote:
Originally Posted by MysteriousRed1 View Post
Thanks Dave, Iím trying to keep the numbers matching on driveline, motor, and tranny in this 64. I pulled the 327 to rebuild this fall/winter and plan on pulling it up to 375-400hp. Do you think this rear end was stock? According to the date codes it looks like it, but itís not gonna hold what I put to it...what rear end dit they use with a327 300hp or the 409?
I believe you will be disappointed with a high revving 375-400 hp 327 and a 2 speed power glide. The transmission (and rear if you don't have something close to the 4.11) will not allow the engine to 'see' its power band.

You also will need headers and a VERY free flowing exhaust to 'realize' the power.

Kinda defeats the purpose of 'numbers matching', in my opinion.

Me? If it were important enough to me, I'd 'dress' the sbc 383 to look like a 327. The high torque in the low end will is much better for the street.

An example:


and:

My 1964 Impala Restoration

Same engine, just more info.

Simply food for thought.

Pete
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post #12 of 12 (permalink) Old 07-20-2020, 05:51 PM Thread Starter
 
 
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Thanks you all for the input, the car is coming along nicely gonna be looking for the rear end it’s gonna need for the HP that’s gonna be made. Don’t plan on taking to the track, but don’t wanna be left at the lights either😜
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