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9 Inch 3rd Member

broncosam

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Feb 8, 2005
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While in the garage yesterday tinkering with my 74 Bronco I crawled underneath to check the axle ID tags and discovered my rear axle has a nodular iron housing. It has a big capital N cast into it. My understanding is that Ford used these mostly in high performance applications. What makes it even more curious is that the first Bronco I bought years ago, another 1974 model, had one in it as well when I bought it. Is this normal?
 

Apogee

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I don't know what they came in historically, but that's cool to get the better N case...though it would be a bit weird to run 28-spline axles in it IMO. Maybe Ford had some leftovers from some other production lines they wanted to use up.
 
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broncosam

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That's the only thing I can think happened. I mean what's the odds of buying two different 1974 Broncos with almost 20 years between purchases and both having the nodular iron center section.
 
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broncosam

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I'm not so sure about pickups. I've had several trucks and full sized Broncos from the late 70's to the early 90's and none of them had the nodular iron center section. Not even the 77 nor the 79 F150 4x4 trucks I owned had it, and I bought the 77, an 84 Bronco and an 85 F150 4x4 new.
 

jamesroney

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Before we all get excited...please understand that there are several different factory Ford "N" housings.

The famous, high performance, heavy duty 9 inch housing from the 60's is the C4AW-4025-B case. This is a very desirable, 3.063 big bearing case. This is the one that is very expensive and well known. It will usually have the Daytona pinion support, and it may, or may NOT have a big "N" cast in the front. The no "N" N case is very desirable, and hard to find.

In 1970, Ford produced the D0OW-4025-B case. It might be a heavy duty case, but not high performance. It can be found in some 1/2 ton pickups, and I've seen them in ambulances. It is a 2.891 small bearing case. It does have the big "N" cast in the front. It is stronger than the C7AW-E case, but with a standard pinion support.

So...you have:
1. C4AW-B "N" case.
2. C4AW-B "no-n" case.
3. D0OW-B "fake" case.

Please don't take "fake" as meaning bad, or weak. It just means that it isn't a true high performance case from the muscle car era. It's "fake" because it isn't as strong (and numbers matching) to a Shelby, Boss, Cobra Jet, Thunderbolt, etc. application...and you can't tell from the outside!

For a Bronco 9 inch, 4.10 and higher...I would rather have big bearings and 35 spline axles. So any aftermarket 3.25 case would be a stronger combination.
 
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