I took the chunk out of my 34 street rod to change the 2.47 gears...to try to get more low end torque. The set up of the car is 400 ford cid, c-6 and 9 inch rear....I found a 3.25 rear chunk and cleaned it up and painted it. As I was doing this, I saw it said c8AW-4668-B on the case. I knew this was a 9 3/8 setup and not a 9 inch. I was told to grind where the ring gear goes into the rear housing, and it would fit. I done all this and it went in perfect. I made the mistake of bolting it in and slid my 31 spline axles in and they did not touch ANYTHING. So I took the chunk back out and seen the spiders in the carrier were something bigger. 35 spline i think. QUESTION--hopefully some of you know this,, will the spiders in the 2.47 setup(c7aw-E,, 31 spline) fit the 9 3/8 setup,, OR, will the ring and pinion from the 9 3/8 (3.25) fit the c7aw-E (2.47 setup) Hopefully I am making all this clear. The 9 3/8, c8aw-4668-B is not helping me at all cause my axles do not match up,, and the axles are custom made for length. So, how much if any, of the 9 3/8 set up will fit into my original C7aw-E case(9 inch) I need HELP !!!!! thanks,, Dan

 

This guy says no interchange between the two, but he's guessing:

Kevinstang's Ford Nine Inch Differential Page +

(about 1/4 down the page)

Comments here from HRM not encouraging:

9 3/8 rear end ? - Ford Motor Forums - The #1 Ford Forum

NAPA bearing for '66 Lincoln, supposedly has a 9 3/8:

Store Locator | NAPA Online

'66 Ford F100, a 9er:

NAPA Online

If you look at the part specs, the dimensions of the bearings are different. This tells me there is no interchange---BUT I'M GUESSING---but based on this, I would stop trying to swap parts between the two, and go back to looking for another 9er or buy a set of gears for the current one.

Now I know this isn't exactly what you were looking for, but it's the best I can do, and I noted your complaint about no responses so I done the best I could. SOMETIMES a new post will draw another response, SOMETIMES from our parts man or others with the FIRST HAND knowledge you want. SOMETIMES.

 

yep differant animal all together.

 

thanks for some answers,, and sorry for the attitude,, I was rather dejected when I got no replies....Thanks again...Dan

 

That's ok, I think we pretty much have figured the 9 3/8s is not going to interchange--may be more answers coming.

Don't worry about attitude--you're good at this point. You ought to have seen this feller a while back who wanted some axle weights. Several tried to find him links, give him estimates etc, and he called us all stupid for not giving him an exact answer. Then he got a little "vacation" and came back and called us stupid again..... So hey, we already know you have some manners, and good luck with your axle project.