I have a 351C with FMX and the 3.0:1 that it came with was perfect for highway cruising. I would go with the 2.75. You'll love it on the highway and the windsor will still give you nice grunt off the line.

 

I thought the same thing, I just didn't know how to bring it up. That's funny right there as Larry says

 

Hmmm Five tries to post a response.

Figured I'd try this one just as a test - is the site acting weird for anyone else today?

The index of posts says I was th elast person to post here, but it disappeared - right before my eyes!

Well if all four of them magically show up later please forgive me.

J!

Ok well this one stuck, so I'll try to enter the info without the links and see if it stays.

I wanted to tell you to check the 9" rear you got and make sure is isn't actually a 9 3/8 inch rear. They are in the same family. In the mid 60s, Ford put these beefed up rear ends in their big Ford Cars and some trucks - like "Camper Specials."

All the parts are not interchangeable and rack/pinion sets for the 9 3/8 are quite a bit more difficult to get.

I have a 390PI with a C6 and a 9 3/8 rear out of a 65 Ford. My rear end gearing is 2.79 to one. It is perfect for the highway. With 15 inch wheels I am travelling 65 mph at 2500rpm. I'm thinking about bolting a 20% reduction Overdrive to it for long trips. That would put me at 2000 rpm at 65 mph (or 2500 rph @ 85 - shhh!). With the horsepower I have, I have no problem with gearing that high - but, torque in the engine mounts just resulted in a failed motor mount cross member. It was understrength though.

If you send me a PM, I'll send you the links for "Kevins 9" rear end page," which has a lot of info and pictures to help you ID your 9". I'll also send you the Ford Differential ID number List (or you can send me your tag numbers and I'll look it up for you). Lastly, I found an rpm/mph calculator which will allow you to enter the ratios of all your gears and even an overdrive and get the MPH @ RPM numbers. That might help with the FMX transmission and your second gear start.

Hopefully, this will stay put this time. I'll try and add the links in another reply.

Good Luck,
Julie

 

Hey Julie,
I haven't been on that much tody but I have had the sane problen as you are having. I think it was about two weeks ago.

 

Here's the links:

Kevinstang's Ford Nine Inch Differential Page +

 

Here's the second one:

Gear Ratio Calculator

 

Thanks for the links, Julie. I've already looked at the sites you list, and am confident that I have 2 true 9" axles.

To everyone else, I appreciate all the responses, and they reflect the varied perspectives of the varied FTE Membership. A lot of the comments affirmed what I already thought, but I wanted first-hand knowledge to help me decide.

I think what I will do is swap in the 2.75, and hang on to the the 3.70 in case I can find someone locally who would be interested in trading for the 3.25 I wanted from the start.

And yes, the thread title was intended to provoke a chuckle. It made you look, didn't it?

 

HI Mr. Mayo,

Well, now they all show up...Sorry for the duplicates - site is retarded lately.

Funny thing is on the post that finally showed up with all three links, the one that decifers the serial numbers showed up on that one, but got edited off when I sent them individually - maybe a copyright thing, virus alert of something??????

I think youwill be very happy with the higher gearing!

Best,
J!