9 inch rear end gear ratio ???

Im about to buy a ford 9" rear end off craigslist. It came out of a '67 Econo. My question is, what gear ratio would be in there now, 4.0?

Also, what gear ratio would be best for cruising at high way speeds? 3.5?

Where can I find a rebuild kit for it? seals, gaskets, etc....

Thanks.

I had the 7" peanut with 4.00 gears. Replaced it with a 9" out of a 66 econo with 3.50 gears. Much better at highway speeds, although you could probably go lower (higher). It went from screaming at 55 to cruising along nicely.

65 Econo, which engine do you have?
Our stock 240 with a 3.00 rear gear works great for us. Not a problem maintaining 70 on the interstate (even 80 with white knuclkes!) and has no problem pulling our little camper from time to time.

No way to know for sure what's in there now except to check. IF, and that's a big IF, it still has the original gears the tag on the door or a tag on the rear axle may tell you.

What's best depends on what RPM the engine is happy at and the size of the rear tires. There are a bunch or calculators online to help. Basic typical gear rules are that the rear tire is 26-29 inches tall, and that a stronger engine can pull a higher (lower number) gear. Anything less than a 3.0 is normally called a freeway gear. This keeps the RPM low and saves MPG, but requires a torquey motor and loses zip around town. Pretty useless in our non-aerodynamic vehicles. 3.0 to 3.3 is typical for a good balance. 3.3 to 3.7 is for less high speed or a less powerful engine or for a bunch of zip around town with the trade-off of higher RPM on the freeway. 3.7 to 4.1 is pretty steep for freeway driving, unless you have a tall (over 30") tire.

There are a number of sources for 9" parts, you can go to the big mail order places (Jeg's or Summit) or go to a specialty place (Randy's Ring & Pinion or Currie) and get more knowledgable help. It is also good to support your local shop, if they have a good reputation.

Gearing is all about horsepower,,,,, it needs to work with what you want it to do and how much torque you can muster, which gets directly to engine size. To use an example, a 300 has a lot more torque than the 240 does, not just the cubes involved. If you could climb a long hill in third with a 240 and 3;50 gears, drop them to 3:25's (like I did) and the truck would start to die out about half way up the same hill. Put in a 300 and now its screaming up the same hill with the 3;25's,,,, so then to tone it down a notch could more than likely now run 3:00's now. Just trying to show the relationship to gearing. Any of the 4:00 gearing was generally meant for low speed grunt type pulling power, not intended for extended cruising at 60 mph, because its screaming again...... the gearing would also depend on what you have for a motor as well as what you have done to it, as well as what you want the truck to do???? Generally speaking, for a stock 200 I have found the 3:50's just about as good as you can get????? but if you are always on flat ground at a higher speed, then you MIGHT get away with 3:25's???? If you have a 170 or a 144, then for sure you would want the 3:50's only......
In regards to a 9" rear axle and changing seals,, BE CAREFUL on the pinion seal!!!!!!!!!!!!!!!! To replace the seal correctly, YOU CANNOT SIMPLY pull the yoke and put in a new seal,,, IT DOES NOT OPERATE that way!!! To do it correctly, you need to install a new crush sleeve, and slowly tighten it UNTIL the inch lb reading to rotate it, meets specs,, if you over tighten it, it will crush the new sleeve to much and leave the wrong measurement. The part # for our 9" pinion seal is #7044.
On the axle seals inspect the seal surface area, I have a half a dozen axles here that are not good because of being all tore up. Also, there are NO SUCH thing as a "seal saver" sleeve for the axles.... The seal number is CR # 13738.
Hope that helps ???
vic