How do I find an 8 3/4 rear in the jy

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Sixpack_Sid

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Looking for an 8 3/4 rear. I am going to the junkyard that has older cars. What should I look for at the junkyard when I cannot get under all of the cars because of the tall grass or tires are gone and they are laying on their frames. Is there a way to decode the VIN that will tell me what rear was in the car? I want to put it into a 75 Duster. Help is much appreciated!
 
Looking for an 8 3/4 rear. I am going to the junkyard that has older cars. What should I look for at the junkyard when I cannot get under all of the cars because of the tall grass or tires are gone and they are laying on their frames. Is there a way to decode the VIN that will tell me what rear was in the car? I want to put it into a 75 Duster. Help is much appreciated!
No rear end codes on the VIN.
 
Smooth round on the rear of the 8 3/4 housing, center gear section comes out the front.

69DartGTS.jpg


0807171733.jpg


0806171639.jpg
 
If you want bolt on.

Your looking for:
66 thru 72 Dart first digit is a L
70? Thru 72 duster, demon etc.
66 thru 69 Barracuda first digit is a B
66 thru ??? Valient. First digit is a V (IIRC)

Look for VINs that have I higher letter in the 5th spot than a D


Looking under the hood look for V8s with a 4bbl

Trailer hitch in the back is also a possibility

66 has the vin on the door piller and is silver in color
67 is on the door piller and is black in color
68 up is on the dash
 
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Dana67Dart is correct, you basically need an A-Body car that came from the factory with a 4bbl engine. Although, I believe that starting in 1974 (could have been 1973) all the A-Body high performance cars, with the 360 4bbl, went to the 8/14" rear end, the 8 3/4 was no longer offered after 1974.
 
Look at the end of the axle hub n the center of the wheel. If it’s flush it’s either a 7.25 or 8.25. If it’s dished in it’s an 8.75. You don’t even have to lay down. Pop of the in cap and there it is.


This is what you are looking for.

D07C4F27-792C-4FE7-8571-568C503950A5.jpeg
 
ll the A-Body high performance cars, with the 360 4bbl, went to the 8/14" rear end, the 8 3/4 was no longer offered after 1974
Agree, I did not know the change over date
 
Dana67Dart is correct, you basically need an A-Body car that came from the factory with a 4bbl engine. Although, I believe that starting in 1974 (could have been 1973) all the A-Body high performance cars, with the 360 4bbl, went to the 8/14" rear end, the 8 3/4 was no longer offered after 1974.
I have to disagree with HSDemon -

The last year for an 8 3/4" rear in an A-body was 1972. That also had a 4" bolt pattern and the smaller brakes. The cars didn't need a 4 barrel engine to come with an 8 3/4", but it guaranteed it. There were 273 and 318 that could be found with them.

Starting in 1973 A-bodies came with 4.5" bolt pattern and B-body sized rear brakes when optioned with front disc brakes. But the rear was an 8 1/4".

(1976 /6 A-bodies may have been available with drums all around and the 4.5" pattern but I don't recall the details.)

Sixpack_Sid - does your '75 Duster have OEM front discs & 4.5" bolt pattern all around or drums all around with a 4" bolt pattern?

 
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Last year for 8 3/4 is 1972 (73 and up 8 1/4 was the "heavy duty" rear - bolt on rear cover w/ 10 bolts)
Any car could be ordered with a 8 3/4. My 1970 Swinger with a 318 2bbl came with one, god knows why since I bought it from the original owner in 1983 when she was 86.
In 1972, since it was the last year for them, they dumped a lot of 8 3/4 rears that were at the factory in what ever they were building at the time. They knew they would continue the 7 1/4 for many more years. I've seen 8 3/4s on 318 and slant 6 cars and even bought a few dead 4 doors just on the value of the 8 3/4 rear.
 
I have to disagree with HSDemon -

The last year for an 8 3/4" rear in an A-body was 1972. That also had a 4" bolt pattern and the smaller brakes. The cars didn't need a 4 barrel engine to come with an 8 3/4", but it guaranteed it. There were 273 and 318 that could be found with them.

1973 A-bodies came with 4.5" bolt pattern and B-body sized rear brakes when optioned with front disc brakes. But the rear was an 8 1/4".


Sixpack_Sid - does your '75 Duster have OEM front discs & 4.5" bolt pattern all around or drums all around with a 4" bolt pattern?

I though the cutoff might have been 1973, but I was not sure. That is why I said that "I believe that starting in 1974 (could have been 1973)" ...
 
Does it really matter?

The op wanted exterior clues to look for.

Post 6 is the greatest exterior clue
 
8 1/4 started in 73 in 340 cars and some 318 cars. This was also the changeover year to big bolt pattern.
I recently parted a 71 swinger slant six car that had an 8 3/4 in it. I had no idea until I got the car home and jacked it up. So never say never, anything can have one in it.
 
Even if there was a way to tell from the VIN, these cars are OLD and a lot of time has elapsed. Anything could be under it. Best to look, even if it's "hard".
 
Thank you for all the replies! You guys really have a lot of mopar knowledge.
 
You may have better luck finding a 65-67 B body with an 8 3/4 under it.

I's only 2" wider than an A body 8 3/4 and basically will drop right into a Duster, Demon, Dart Sport or 67-69 Barracuda.

People will tell you you have to move the spring perches but you don't.

Fitting into an A body with more restrictive rear wheel wells is more challenging, but can be done.

If you have disk brakes, it will move the rear wheel track out to be the same as the front.
IMO this is a better look.

In my experience all 1966 B body cars (Coronet, Satellite, Belvedere, Charger) with a v8 engine had one- usually with a 2.94 gear. I am not completely sure about 273 cars, though.
In 67 small v8 cars except wagons and Chargers are more likely to have a 7 1/4.
I know nothing about 65 cars.

...and they will be big bolt pattern
 
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I have to disagree with HSDemon -

The last year for an 8 3/4" rear in an A-body was 1972. That also had a 4" bolt pattern and the smaller brakes. The cars didn't need a 4 barrel engine to come with an 8 3/4", but it guaranteed it. There were 273 and 318 that could be found with them.

Starting in 1973 A-bodies came with 4.5" bolt pattern and B-body sized rear brakes when optioned with front disc brakes. But the rear was an 8 1/4".

(1976 /6 A-bodies may have been available with drums all around and the 4.5" pattern but I don't recall the details.)

Sixpack_Sid - does your '75 Duster have OEM front discs & 4.5" bolt pattern all around or drums all around with a 4" bolt pattern?


I have even seen them in /6 cars original.
 
Heres a video from one of our fellow members on swapping a B-Body 8.75 into an A-Body.

 
Just got back from the yard I only found 73 d 100 with 8 3/4 . Thanks for the replies!
 
Just got back from the yard I only found 73 d 100 with 8 3/4 . Thanks for the replies
Kind of what I expected you would find.

Your options now are buy a housing: 600 to 1000 depending on condition.

Center section: 100 to 500 depending on condition and gear and open or not

Axles, 100 to 500 depending on used or aftermarket.

Backing plates, drums, brake hardware: 300 to 500

U bolts and shock mounts: 100 to 300

1200 to 2800 depending on condition and components


You could look for a parts car and sell the parts you don't need.
 
I have said it before, and I will say it again. This right here is shade tree bullshit. If you can weld, there's no reason for this. And if you can't weld, you shouldn't be doing this swap without going to someone that can.

Screenshot 2023-01-07 at 11.48.00 AM.png


Stock perch distance on an A-body is 43", center to center. Stock perch distance on any of the '65-70 B body rear axles is 44". That's offsetting a 2.5" wide spring by a 1/2" (20% !) if you do this redneck drilling operation, or putting a 1/2" worth of side load on the springs (which also decreases your tire clearance by a 1/2").

Can you do this? Sure, you can. But it will absolutely decrease the performance of your springs. If you don't notice that, well, you probably just don't know what a properly working spring is supposed to feel like. The other thing about this is that B-body and A-body perches are not welded at the same angle, so if you use the B-body perches your pinion angle will change, and it will likely not be correct (although there's more to this depending on how your car is set up for ride height).

The only right way to put a B-body 8 3/4 in an A-body is to move the perches. And if you're moving the perches, you can get a 1/2" spring offset kit from DoctorDiff, mount the perches at 42" c-c and GAIN an extra half inch of tire clearance, instead of losing a 1/2" and/or compromising the function of your springs. If none of this mattered, why would the factory make sure that the perches were the same width as the spring? You could save a bunch of money on production by making little skinny perches, or by welding all the perches in the same location (one tooling fixture instead of several) and just adding a big slotted hole for the spring bolt.

And this is the problem with the internet. You can always find someone that did something stupid and didn't die, so they assume it's ok. No, it's still stupid, it's still bad practice, and it's still bad advice.
 
My son bought an Explorer 8.8 with a 3.73 trak lok and disc brakes out of the junkyard for 150 bucks for his 67 notchback. The price is right and it is a strong differential.
 
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