Technical What mopar rear end is equal to ford 9"

I am looking for the equivalant of a ford 9" but for a Mopar / Dodge. I am building a 360 with tranny,drive line, and need the rear end match. Not sure what to go with.

 

The 8 3/4 is the closest.
Drop out center section
Pretty tough
fairly common


A couple links-
https://www.jalopyjournal.com/forum/threads/dodge-8-3-4-strenth.458086/

https://www.hemmings.com/magazine/mus/2004/10/Mopar-8-3-4-inch-rear-ends/1280934.html

 

Suggest you do a little on line research, their are certain casting numbers on the center sections that are believed to be stronger than others. Not sure if it really matters, but look for the info and you can be the judge.

Ray

 

Maybe this will help....

 

Get a 8 3/4 center section { 742} with a dana power lok . The 489 center sections have Auburn sure grips . They are okay for medium horse power. But arent rebuildable. Stay away from the 741 center sections.

 

What's it going in? Will the 360 be making a ton of power? What are your driving habits? There are 489 cases. .741 and 742's People will argue which is better. Some have a crush sleeve for the pinions. .some are shimmed. They are all perfectly fine and strong enough for a mild small block and a auto. ..with the occasional burnout. Stay away from the tapered style axle drum combo. Just a little more hassle if your NOT going for originality.

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If I could go in the 9's repeatedly with a 489 case/chunk what have you, I think you'de be alright...

 

put a 9" ford in it.

 

The mopar 8.75" is a great rear end and fine for darn near anything you would call a "street car", squirrel's efforts excluded!
That said, if you can get a 9" for the application within your budget, it offers a few pluses simply due to it's commonality in racing and rodding. They also share the 5x4.5 PCD.
Issues are:
1. Bearings are tapered and handle loads better than ball bearings. However, they require adjusting with parts that are a bit tough to find, and really limit rear disc selection. There are ball bearing conversions ("Green Bearings"), but then you lose the 'better' setup.
2. Better angle on the pinion, but is not supported by 3 bearings. Unless this 360 is fire-breathing, this should not be an issue.
3. Less aftermarket support - as with all mopar stuff, there isn't as much out there and the parts are going to be more expensive than similar Ford stuff 'cause they don't sell as many. Look at all the different ratios for the 9" VS the mopar. Look at the E-brake parts for rods. Check into finding the 'good' big U-joint yoke.
4. Made in the mid-60s to the mid-70s. Earlier ('65 and back) have the tapered axle ends you have already been warned about. Still has support, but it is not going to get better. Ford stopped production of the 9" in '86.

 

Not disagreeing with others who have made recommendations, but unless the removable carrier (chunk/pumpkin) is important to you, consider the plentiful, inexpensive and stout Ford 8.8" rear axle. Lots of ratios and widths, depending on application.

Ray

 

I don't have any experience with the 8.8 that Ray mentioned, but have to wonder why some have made the point to go with the 9" or the 489-only Mopar??? geez..you guys think he needs that in a family touring sedan with A/T? He's not side stepping the clutch at 6k rpm with slicks, for crying out loud..

 

The 741 case uses a 1 3/8" pinion gear. The 742 case uses the 1 3/4" pinion gear and the 489 uses an 1 7/8" pinion gear. The first two use shims to set the pinion bearing preload and the 489 uses crush sleeve.

Now, I have beaten the death out of the 741's because you could find 3.91 gears in the A100 pickups and we used to pick them clean and most came with a posi unit. I never broke one behind my 340 4 speed car as a late teen early 20 year old and I was rough on it. Same for my buddys 383 B body, same diff, no blown up parts.

The 8 3/4 is a great piece and will work well behind your 360 motor and 727 transmission.

Cliff Ramsdell

 

Mopar saw fit to upgrade to a Dana 60 on the big high performance motors with manual transmissions. But the 8-3/4 will take a lot.

 

By the time you beef up the ford 9 inch to handle the power. You are at the same level of a 489 case mopar 8 3/4.
They do argue 742 and 489 case. But if you swap to the trutrac suregrip. Who cares on which case.
741 case will also handle a lot as they were behind a hemi with the ramchargers drag team
The 8 3/4 was behind automatic hemi cars. Manual trans came with the Dana 60.

Next in line if you never want another issue. Go Dana 60.

The only thing the ford 9 inch has going for it is the aftermarket support.
Moser engineering does a lot for the mopar 8 3/4

 

With a mild 360 an 81/4 is plenty tough as well


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The dakota rt has a stout rear if you want a modern style without the drop out and disc brakes.

 

The Dakota RT has a 9 1/4 and 6 bolt wheels.
If you are building a street ride, any 8 3/4 will be fine, if you can find one in good shape that you can afford.
The Ford 9" has a lot of aftermarket support, they are easier to find, but also not cheap.
If your building a bruiser and plan on heavy abuse, its hard to beat the Dana 60 (9 3/4").
A more readily available rear axle is the Mopar 9 1/4. There are fewer gear choices, and it has a few drawbacks. You have to watch the wheel bolt pattern, there are a few different sizes of the 5 bolt pattern, and there are the 6 bolt wheels as well. They were plentiful under 1/2 ton pickups.
A Mopar 8 1/4 is another possibility, but they could be a bit light duty for something possessing power and traction. Sure grips (posi) and good gears are not easy to find in the 8 1/4.
A lot of guys are going with the Ford 8.8 these days. A lot of Explorers had them with 3:70 gears, limited slip, and rear disc or drum brakes. You will have to remove the coil spring brackets and add the brackets for your leaf springs. Gene

 

If you plan on going in the nines put a Dana 60 in and forget about it. I have destroyed so many 8/34 Danas go in everything I build now. Keep it all mopar. By the time you build a stout nine inch the only thing left that's Ford is the pinion nut.

 

A Dana axle is not a Mopar axle. Dana/Spicer sold axles to anyone who had money.

 

When It has the three bolt pad for the snubber it becomes a mopar only axle. Not to mention a mopar serial number and mopar part number. No one else used the three bolt pad. Are my 3705s max wedge carbs not mopar because Carter made them? How about my fiberglass kit for a altered wheelbase dodge made by plaza fiberglass?

 

8 3/4 was strong enough for a front engine dragster I drove for a guy and it was a clutch car. It should be strong enough for a 360 automatic . Just build it with good parts.

 

I have 8.75 rears in both mine. It has Less rolling resistance than a 9" for sure. The 9" is a power house but the 8.75 with a 489 case setup blows it away. I have ran 10 years on a 741 or the x housing and its been real good. Both are from the 60s. Only downfall is finding brake shoes locally, you most likely will have to order shoes in if needed. Rest is just make sure the outer axle bearings are greased correctly, the thrust is set and you are golden. 742 case is great for the occasional run down the strip, and street beating, but if you just want to cruise with some burnouts etc the 741 will be fine.

On the center section you can tell what you are getting by the raised letter on the side of the section housing.

X is 741
2 is 742
and 9 is 489

Price for a 1 or 2 is normally about 200-400 bucks complete, the 489 complete starts about 600 give or take, if you find a sure grip posi 3.23 it aint cheap.

 

8 3/4 will take a big 383 hard slamming for years without repairs. So, the 360 will be fine.

 

I`ll add that you can buy a crush sleeve eliminator for the 489 case.

 

742 case with 35 spline axles is a tough combo. I handled close to 1000 hp in my Avatar FED. Current owner is running an alky injected BBC with zero issues. It is a light car though.

 

Even tho the 742 has a 1 3/4 pinion vs the 489 1 7/8 pinion the pinion bearing of the 742 is larger. and for racing purposes the gear selection for the 8.75 is very limited in good material gear sets, Lots of time we take a street gear (too hard) and anneal them a little for impact resistence

 

This.... Like Ray says, there's lots of them out there (found under Explorers, Ranger PUs, and Mustangs), cheap to buy (around here they can be had for $150), readily available parts, common ratios from 3 flat to 3.9, can be found with or without posi and drums/discs, and most are narrow enough to fit under a 'vintage' car.

 

my plan is not to hotrod the car, I want to leave the look it has now, I want the reliabilty of the V8 with the drivabilty.

I am not sure if I should go with automatic or stick shift, the car is stick now, and stick is fun, but if I am not going to do hotrod stuff, why keep it stick.

the rear end and all drive train I would like to keep as a mopar 100% . I keep going back and forth with the engine swap either keep flat 6 or pick up this 360 and build it up.

but the rear end either way will not be romped on, I will drive the car like an old car as the suspension is not built for hot rod standards. so the rear will be on the leaf springs.

 

first thing is to figure out the wheels/tires, then you can figure out the width of the rearend, then you can start your search. If you want it to be MOPAR and look like an older build (traditional), then the mid 60s-early 70s 8-3/4 is the way to go.

 

My goal is to keep the same stock rims and tires, same height of stance, but just updated engine/tranny/rear end. the more I think of it, I want to keep the flathead 6 but update tranny and rear end. but I just got a 360 for $200 so I have a motor that I will build and decide to either sell or put in the car, but for now the rear is going to be my 1st goal to get the rear end gearing corrected.