Hello Everyone,
I Have Been Following Some Of The Posts About Increasing Road Speed Via Rear End Gearing With Interest. I Have A '63 F100 223 With 3 Speed, With 3.89 Ratio. I'd Like To Install Either A 3.25, Or 3.50. I'm A Bit Confused About The Difference Between Replacing Just The Center Section From Another One, Vs. Replacing The Ring And Pinion, Which I've Read Is More Costly. When You Replace The Third Member Only, Don't You Still Need To Unbolt The Ring Gear And Replace That Out Also, Like A Matched Set? And If You Do That, Don't You Still Need To Then Adjust Backlash And Pinion Depth, Like In The The More Involved Way With Replacing With A New Ring/pinion? Or Does Replacing The Center Section Only Mean Leaving The Old Ring Gear In Place. Please Advise.
Thanks, John

 

John, it depends on which axle you have. If you have a Ford 9" rear, you can swap out the entire center section or punkin without removing gears. Ford 9" rears are found in the F-100 series, and always have 5 lug axles (from the factory, anyway).
The F-250s, though, have a Dana or Spicer axle, and it is completely different. These axles do not have a removable punkin. To change the gears, the axle must be disasembled and new gears installed. These axles usually have more than 5 lugs.

Now you cannot always be sure that a 5 lug axle means you have a Ford rear - some Dana axles have 5 lugs. To be sure, look at the rear of the axle housing.
If it has a rear plate held on by bolts, you have a Dana.
If the rear plate is part of the axle housing and cannot be removed, but instead, the nuts are in the front of the axle holding the punkin in, then you have a removeable Ford 9" rear.

My guess is that you probably have a 9", but you will have to look to make sure.

As for the choice of gearing, I would most definitley not go lower than 3.50. That little six is stout, but not very powerful. That is why you have a 3.89 instead of something lower.
I put a 3.25 into my '66 F-100 when she had a 352 V8 and a three speed, and it was terrible starting off from a stop. I had to feather the clutch quite a bit.
Your 223 may not be able to handle it well at all.
Today, I have a 2.75 in there, but in front of it now is a 460 with a C-6 - with power to spare.

 

Let's define terminology (Ford name first):

Carrier housing - the whole removable portion of the 9" unit. aka: pumpkin.

Differential case - the smaller unit that the ring gear bolts to. Sometimes referred to as "differential carrier".

I agree with banjopicker's comments 100%.

 

Thanks To Those Of You Who've Replied To My Post In Such A Timely Manner. After Writing My Original Post, I Did Some Visual Investigating Of My Differential. I Notice That The Front Part, Where The Pinion Housing Is, Including The 10 Bolt Detachable Front Housing Is All Red In Color, Whereas The Rear Housing, Including The Axle Housing Is Black. The Code Off The Front Bolt Housing Is: 2h27. On The Pinion Housing: C2aw4668. I Suspect The "pumpkin" Had Been Replaced Before My Ownership. As A Further Test, I Rolled The Truck In Neutral, After Marking The Driveshaft, And Stopped After One Wheel Revolution. The Driveshaft Rotated 3 And 1/2 Turns. A 3.50 Ratio. I Appreciate Any Info On The Above Codes, As To Identifying Year And Application Of Center Section. You All Know How It Is, When You Don't Own A Vehicle Since New. You Discover Things Over Time. Thanks Again For All The Info.
John

 

Ooops, I Forgot To Mention. The Speedometer Driven Gear, Off The End Of The Speedo Cable, Is 17 Tooth. I Remember That For A 3.89 Ratio, It Calls For An 18 Tooth, So It Would Make Sense If I Have A 3.50 Ratio, To Have A 17 Tooth.
THANKS AGAIN, JOHN

 

The 9 inch rear end was introduced in 1957, and both cars and light trucks came with them.

C2AW-4668 = 1962 Ford Galaxie

 

Thanks For The I.d. On The Unit, Bill.
John