It has a 3.70 ratio, wondering how late it will accept gears such as 3.25 which appeared in later years, without having to uproot the whole housing.
Thanks as always.

 

Any Ford 9" with 28 splines should work. You just use the original yoke.

 

I thought 9" rear ends were for cars. I've been quite confused on that issue for years but never bothered to inquire much. The last F100 I had was at least 10 inches but that included the casing and I don't exactly know what 9" means if that's for internals or what.

 

The ford 9" rear end has been used in cars and trucks for years and years. Something like 1957 - 1986, maybe longer. They are quite available and still made today by aftermarket companies. Some have 31 spline and some 28 spline on the ends of the axles. The 57-60 rear ends have 28. The 9 inches in referring to the diameter of the ring gear that the pinion gear drives. The ratio is the number of teeth on the ring gear divided by the number of teeth on the pinion.

Hope this helps.

 

Yes it does help. Thanks very much. It opens my eyes on things.

 

You can indeed swap in a newer 9 inch but you will probably have to do some changes as far as the shock mounts. You can always cut them off your existing and put them on the new one.

 

When I changed mine, I only changed the differential or "third member". No need to change the housing. Pull the axles, unbolt the differential, change the flange (or yoke) on the differential, bolt the new differential on and replace the axles. I also suggest replacing all the seals (2 axle and 1 pinion). fill with oil and you are in business.

 

Well, you are right, that is entirely possible, several ways to approach it.