I've looked at a few early 60s slants recently and they each had noisy rearends.

What percentage of 35-40 year old 7 1/4 rearends have this problem?

Mine's 42, ('64 2.94 open 7.25") and doesn't seem to make much noise.

Now, where's some wood to knock on ... ?

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

I hope to buy a running car with a quiet rearend so I can drive it up a steep, narrow driveway and park it end-to-end with my 63.

Then I hope to swap rearends with the wheels still on them.

I wonder if a higher percentage of the 63-68 REs are going bad than a newer 70s-80s rearends.

My goal is to put a rearend on it that will make it a reliable car again.
It's been a time-bomb ever since I rebuilt the front end and the rearend started to go bad.

I'd prefer a 2.93 from a 63-68, but not if I have to sacrifice reliablity.

How are we defining "bad" noise?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

The bad noise in mine has been reliably diagnosed (joshie225) as pinion bearing.

It starts out as how pitch rumble. It gets loader and higher pitch at freeway speeds.

Two of the cars I drove had a similar noise up to 35-40 mph, the other one sounded like mine, but I couldn't get it above 25 mph.

I'm really bad at describing the noise and I have zero experience with pinions or rear wheel bearings going bad.

I wonder if I could tell the difference between the two, since I'm tone-deaf and going regular deaf and haven't heard a wheel bearing.
I'm pretty sure the ones I test-drove had the same noise as mine.

If you could test all the 63 to 76 7.25 rearends on the road today, would there be a higher percentage of the 1965 rearends with pinions going bad because of the age factor? Or is there some design improvement that would make the 1975s less prone to this failure?

I've got 2 Darts, a '67 V8 convertible, and a '72 slant Swinger. Both have 7 1/4" rears. The '67 moans when you're on the gas, and it's exacerbated by the convertible top (it's not so loud with the top down)

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vm

pinion going bad noise

My 3.23 in a 65 Dart went ~300,000 miles and it got noisy towards the end.
I am assuming you are going to remove the wheels first?

Support car on jackstands at spot in front of springs so the wheels are barely off the ground
Disconnect the brake stuff and driveshaft
Undo the U-bolts
Then lift the pumpkin and put wood under the wheels to lift the axles off the springs
Disconnect the leaf springs at the rear connection
Roll the rearend to the other car.

Lots of wood, lots of jackstands and jacks, almost zero lifting

Typical 7 1/4 rear noise, they are really easy to screw up. I have broke three in my Duster. I hope to upgrade to a 8 1/4 after I get it running again.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

I thought the rear was shot in my 63 Dart with the noise it was making but it turned out that the axle bearings were toast.The gears looked good but the bearings were completely dry with a smattering of rust for good measure,it sounded like a airplane was landing in my trunk.I replaced both bearings and seals for about $60 and now my differential is quiet again.
HyperValiant

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1960 Hyper-Pac Valiant(rolling test-bed)
1963 Valiant V2OO(Son's summer project,- he just turned 15 )
1972 Valiant 4dr(Daughter Kelly's repair in progress)
1974 Valiant (v8) daughter Kelly's work in progress

I knew mine was shot when I took the cover off the rear and the spider gears (or what remained of them) fell out.

That is why you should not drive through the burnout box and get your tires wet. I have broke all three of mine when the tires start spinning and suddenly get their grip back. Sounds like you have a trunk monkey.

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

IME, most RWD Mopars tend to have some rear axle noise. Usually just a moderately unobtrusive sing on light throttle between 30 and 50 mph, just enough to let me know the rear axle is still back there and hummin' along. But yeah, any more noise than that and it's time to scout out a replacement.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

The pinion bearing in the Valaint has been on its way out for years (mebbe 5) ....it just gets a teeny bit worse every day....I dream of a Exploder Trac Loc 3.55 ratio with discs

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Sandy, do you ever get down to the lower mainland? I got my explorer rear in Chilliwack, at the pick n pull for 115$.

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Excuse me, does this smell like chloroform to you?