Rear end options? Best bet?

[mrkt09]

Currently I have a 2.76 open geared 8 3/4 and am wondering if I should regear it to a 323 and add a locker or swap in a Dana 60. The Dana will run me a bit more money but the stroker I'm building should come to around 600-650 at the crank. Not looking to grenade another rear end if I do not have to so I'm looking for advice

 

[commando1]

You're spending obscene money to build a monster, spend the money on the Dana if you can find one.

 

[moper]

Call Dr. Diff - Cass Eslick and tell him what you want for gearing, how wide it has to be, and what brakes you want. IMO - the C bodies are too heavy to run an 8 3/4 behind something that makes serious torque. You're just asking for sheared axles and bent tubes because the mass is too great. You might want to look into a Gear Venddors overdrive unit - I don't think you can get a gear ratio higher than 3.54:1. A set of 3.54s with an GV will drop the rpms a little more than a set of 3.23s would - albeit at a much greater expense.

 

[bluefury361]

Ford 9" ......... Cheaper then a Dana and much easier to service. Likely stronger then a Dana too.

 

[Landyacht]

What cubic inch stroker are you building? What size cam? What heads? What intake? Any porting work? I'm currently running a 470 stroker in a C body that's pushing just under 500 hp at the flywheel with a 240 degree duration cam and dual plane high rise intake. I started out with a 3.73 gear and it didn't seem to get it for me. Switched over to a 4.10 and was finally satisfied with the performance. These C bodies are heavy cars and need a really high rear end gear to get em down the road. 3.23 seems a bit low in my opinion.

 

[moper]

The FAB9 is a great rear too - and more gear choices. It's not "Mopar", but neither is a Dana 60 in a C body...lol

 

[1969vert500]

I know this is a side note but always wondered if the 9.25 C body rear was stronger than an 8 3/4? I have several of them and just kick them to the side and never think of using them in an C bodies.

 

[mrkt09]

What cubic inch stroker are you building? What size cam? What heads? What intake? Any porting work? I'm currently running a 470 stroker in a C body that's pushing just under 500 hp at the flywheel with a 240 degree duration cam and dual plane high rise intake. I started out with a 3.73 gear and it didn't seem to get it for me. Switched over to a 4.10 and was finally satisfied with the performance. These C bodies are heavy cars and need a really high rear end gear to get em down the road. 3.23 seems a bit low in my opinion.

The stroker is a 512 Stroker, 10.3:1 comp, .574 lift Comp cam 110 lobe sep, 284/284 duration, Max ported super stealth heads, edelbrock performer RPM (ported) also have a victor intake. The reason behind the 3.23 is a semblance of highway ability while not revving to the moon. I have a second 742 casing as well that I could flip in and out. Called strange about axles and they have a set for the 8.75.

 

[mrkt09]

The FAB9 is a great rear too - and more gear choices. It's not "Mopar", but neither is a Dana 60 in a C body...lol

My going for a dana 60 was purely because other Mopars did use one and I would love to see one in a fury (kind of a poor mans T/A package)

 

[commando1]

I know this is a side note but always wondered if the 9.25 C body rear was stronger than an 8 3/4? .

Absolutely.
Ask a gabillion Jeep off roaders....

 

[70bigblockdodge]

9.25 is a great rear and now with a tru-trac diff is a really good unit.

 

[moper]

With what you have listed for parts - I think any factor yrear will not survive if you plan on putting sticky tires on it or racing it (yes, even on the street). The issue is not the gear strength, but the integrity of the caps, the axles themselves, and the axle tubes. 550pound feet at the crank, with a set of sticky tires, in a 4000+lbs will twist the ends right off the axles over time. Assuming the carrier doesn't deflect and the gears break. Or the axle tubes bend.

 

[commando1]

Or put in a Ford 9".... ;D

 

[Big_John]

9" Ford is the best choice.

Then again... I don't think 3.23 gears are the way to go with the engine you are building, especially in the heavy c body. Either more gear or less engine.

 

[Landyacht]

The stroker is a 512 Stroker, 10.3:1 comp, .574 lift Comp cam 110 lobe sep, 284/284 duration, Max ported super stealth heads, edelbrock performer RPM (ported) also have a victor intake. The reason behind the 3.23 is a semblance of highway ability while not revving to the moon. I have a second 742 casing as well that I could flip in and out. Called strange about axles and they have a set for the 8.75.

I would go with at least a 3.73 bare minimum and save up your money for a Gear Vendors overdrive. Despite the large displacement of your engine you're still going to be dealing with some manifold vacuum issues . As for what type of axle you should use whether it be a 8.75 or a Dana 60 I really couldn't tell you. I do know that the 489 castings where considered the strongest out of all Chrysler 8.75.

 

[1969vert500]

9.25 is a great rear and now with a tru-trac diff is a really good unit.

I have never really looked at these as a good rear since they have been in later cars but I guess I am wrong. I have a guy with a 73 fury that has a 400 in it and a sure grip 9.25 rear. It is rusty in the pans and trunk and that is what I wanted so I passed on the car. maybe I should pick it up if these are good for C body cars. Will they swap right into 69 or 70 models? He only wants $300 for the car so I would think the rearend with suregrip and the 400 should be worth that and scrap the rest.

 

[commando1]

The perch mounts are the same so it should bolt right in.
And a 3.55 used in most Jeeps are commonly available.
BUT, are you SURE that 1973 has a 9-¼??
Most are 8-¾ as the 9 was only used on very late builds of the 73 MY.

 

[1969vert500]

BUT, are you SURE that 1973 has a 9-¼??
Most are 8-¾ as the 9 was only used on very late builds of the 73 MY.

Yeah it looks like a 73 and he said it was a 73. I have not laid eyes on it yet in person but he said the rearend drops out the back and has 10 bolts on the cover. Here is a pic of the car.
I also picked up a 73 polara last week that was a 400 2 barrel that has the same 9.25 rearend in it.

 

[mrkt09]

Well I agree that it could be a large issue with axle strength, but note I was looking at replacing them with a pair from strange. Also, curb weight of a 440 Fury on 1966 was closer to 3700 lbs. Vacuum for ancillaries is being ran by a hysroboost unit.

 

[mrkt09]

Never really ran any Ford rears always went Dana. Any specific that would work best? Torini?