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Discussion Starter #1
Hey guys! I'm going to a swap meet tomorrow and I'm looking to upgrade my 1970 Skylarks rear end from an 8.2 to an 8.5. I can already distinguish between an 8.2, 7.5, and 8.5 no problem. Here are things I need to know:

what will bolt right in? what car would they come from? (I know BOP axles won't have an issue, but I am also open to corp 8.5s)

What measurements am I looking for to bolt right in? I've heard both 62 inch and 62.5 inch. Is this correct? what is this measuring from? (I.e. drum to drum, or end of axle tube etc)

any OTHER measurements there may be to double check.

ANY serial numbers will be usefull!

Thank you guys so much! I'm excited to see the swap meet!
 

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You want a bolt in, you’ve got a rearend in the skylark.
Whip out your tape measure and measure yours.
And take some pics of it too.

Where are you finding a swap meet that’s happening? The Covid has shut down most everything.
 

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Explorer 8.8" rear axle will be a dirt cheap axle to buy, and is 59 1/2". Stronger than an 8.5". 3.73 gears are pretty much standard, but 4.10's can be found. Many have traction lock.

Fix the bolt pattern issue with some dual bolt pattern wheels, and the offset at the same time. It also gains you disc brakes
 

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High Performance Rear Ends
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The ONLY rear ends that will bolt into your car are '64 to '72 A body rear ends. The '64 to '67 rear ends are 60 inches wide over all and the '68 to '72 rear ends are 61 inches wide over all. Those 62 and 62.5 measurements are wrong.
 

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More for Less Racer
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The only 8.5" bolt -in is the 71-72 Buick Skylark and Oldsmobile Cutlass....no other 8.5 from anything else is a bolt in..

You might try to research and find out if the upper cast ears on the '73-77 A-body(Monte Carlo, Chevelle/ Malibu, Cutlass, Century/Regal, Grand Prix/Lemans) are on the same angle and location...this would make it possible to use one of those housings for a core to narrow and move the outer suspension brackets/spring mounts to the correct location.
Those rears are the ones that are 62"+ wide.

Again, I have no idea if the upper ears are compatible.

The 8.8" Ford isn't compatible because those upper ears are in such a different place and angle.

Cost of new axles and all the rework starts to put this out of the budget catagory though, especially if you can't do the narrow and bracket reconfiguration yourself.

You seem to keep not wanting to absorb the fact you are looking for a rather rare rear axle assembly if you are looking for a simple bolt in 8.5" solution.
 

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High Performance Rear Ends
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I don't know what you are using for power, but the 8.2 BOP rear end that is in your car can handle most street use. If you need something stronger then the 8.5 isn't going to be much better in stock form. It still has the same 28 spline axles as the other 10 bolt rear ends. You would need to replace EVERY part inside it to make it much stronger. A stock Chevelle 12 bolt is stronger, but still has it's limits. If you are going to make a lot of power and race it then you need to forget swap meet rear ends and go to an after market 12 bolt, S60 or a 9 inch. The after market 12 bolt housings are much stronger than the Chevy housings, and the S60 and 9 inch are even stronger.
 

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Discussion Starter #8 (Edited by Moderator)
He’s doing a fantasy twin turbo bbc build.
With cheap parts!
I don't know why *****************. I'm asking all these questions because I don't know. I'm building my first motor, and I haven't bought any parts for it as I'm still in the planning stage. I am asking every question possible to ensure I don't screw up. Is that not the point of a forum? To make sure I know what to do?

I AM taking people's advice, so don't act like I'm not. I've learned that a 550 horsepower 454 build on a low budget is near impossible, so instead i've settled on shooting for 400

As for the differential I'm searching for: yeah, its on the rarer side. But I'm going to a swap meet to try my luck. Which is the whole point of a swap meet in the first place, to try and find the parts I need.

I don't know why you feel the need to come on my page and look at all my past posts just to mock me, but find somewhere else to be a jerk and let other people actually help me. Your advice was good and comes from experience. I'm gonna listen to it for sure. But stop *******************
 

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I’m not being a jerk!
Just deal with reality.
You keep changing the build.
That makes it a ‘Fantasy’.
You are entertaining though!
 

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Julianskylark: Name calling of members will get you suspended from this board. First warning since you are new here. I edited your post to remove the name calling.

RWENUTS offered his opinion on your engine build. I understand your dislike for that opinion.
 

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Discussion Starter #11
Julianskylark: Name calling of members will get you suspended from this board. First warning since you are new here. I edited your post to remove the name calling.

RWENUTS offered his opinion on your engine build. I understand your dislike for that opinion.
You're right, My apologies. I let my frustrations get the better of me. will not happen again
 

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Discussion Starter #12
I’m not being a jerk!
Just deal with reality.
You keep changing the build.
That makes it a ‘Fantasy’.
You are entertaining though!
I apologize for that outburst. I let my frustrations come to a head and I shouldn't have done that.

However, I'd ask that you keep the "look at THIS guy" comments out of here. The way it sounded felt as if you were mocking me. The build keeps changing because I keep learning. I'm just trying to ask a ton of different scenarios so I don't make mistakes. I've never built a motor before, and I want to see just how far I can push everything.
 

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High Performance Rear Ends
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If 400 HP is the goal and it will be used on the street then you could make a few upgrades to the 8.2 that you have and it should be fine. This is the same rear end that was used in the 455 Stage 1 cars. A good after market differential, some new bearings and possibly a gear swap should do it. If you plan on using slicks with a 4 speed or a trans brake then you may need to upgrade the whole rear end to something larger.
 
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