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Rearend swap?


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What rearend is good to swap in a 1948 Plymouth special deluxe that has the same bolt pattern year make and model?


Edited by beaker31
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How about just changing the differential carrier?

It’s a lot less work and your car is still stock.

You can get a 3.53 ratio easily from one of the Mopar V8s up to 1956.

Somebody said they were too hard to find. It took me all of 5 minutes to find 4 in the same wrecking yard.

While I was looking I found a rare positive ground 6 volt Delta Mark Ten CDI, so it wasn’t a bad afternoon!

My local Craigslist had an advert for a pile of the up to 56 rear ends for free, come and get them!

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I used an early Falcon 8" but those are getting a little hard to find.

8.8 Fords are a good fit and plentiful

8.25 Mopar out of a Jeep 

8.75 post 64 is supposed to be an almost bolt in

In any case you will need a new driveshaft made, details about that are all over this forum.  You'll be happier with modern u-joints anyway

Any of these choices will get you better drum or disc brakes


As far as being more difficult to swap the rear axle vs. regearing?  I would have to disagree, it's easier to swap the rear axle than busting stubborn drums off.

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58 minutes ago, Adam H P15 D30 said:

8.75 post 64 is supposed to be an almost bolt in


They are many different width 8.75's post 64.  A body, B body, C body in order of width.  Not sure where the truck versions fall or the E bodies.


Not sure how accurate this chart is




1 hour ago, Adam H P15 D30 said:

As far as being more difficult to swap the rear axle vs. regearing?  I would have to disagree, it's easier to swap the rear axle than busting stubborn drums off.


Not to mention getting better self energizing drums, if you that route.

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If you have the right tool the drums are easy to get off. I bought one of those cheap Chinese hub pullers because it looked like an old American one.

Could not get the drums off. Then a friend gave me an old one he had used. The main difference was heft. This thing is heavy!

I set myself up for a tough afternoon of beating on this thing. BAMM! It came apart just like in the movies!


There is a thing I've been thinking of. The Model A guys are now getting 12x2 inch Bendix type backing plates ( and Lincoln Drums ) reproduced in China to replace the stock mechanical brakes. The whole setup is like Lincoln Zephyr brakes only with the self energizing Bendix system. Some may know it's really easy to add the self adjusting feature as well. What attracted me to this is the possibility of drilling them to fit the Plymouth steering knuckles without having to change them to Chrysler pieces. 

Next up would be to find a brake drum to substitute for the Chrysler drums that you could rivet to the Plymouth hubs. The supplier to the parts houses is in California and I figured I could take a Plymouth steering knuckle to them and see how they fit. In this way you could get all the advantages folks see in the Bendix system with off the shelf parts and retain drum brakes. The rear brakes can be had with cable parking brakes if desired. It kind of checks all the boxes. My only complaint is the cost maybe higher than finding used Chrysler brakes. 


Lastly if you want to know what the gear ratio is in your rear axle here is a photo of a cleaned up housing. You will find it stamped on the flat under the fill plug. They didn't always stamp them the same way or with the same size stamps but if you will look you will find.



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On 1/21/2023 at 8:34 AM, FarmerJon said:

I didn't have any trouble getting my rear drums off, but apparently I didn't do it right, because I didn't use any special tools.

I just loosened the lug nuts a little, and did a half a dozen donuts in the parking lot. 



A caution for all, do not forget to put the cotter pins back in! I would add that you shouldn't reuse them either.

When you lose a wheel it is always in the middle of an intersection and its mighty hard to find a jack that fits under a car without a wheel.

Don't ask me how I know this!

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