Technical 9" Ford Rear axle interchange question

My 1959 F100 has a 3.89 gear ratio. I would like a more highway friendly one, like a 3.23 or 3.42. What other 9" center sections will interchange with the one in My truck?

 

Any center with a 28 spline

 

Axle splines are the determining factor. 28 or 31. Yours should be a 28 spline job, most common and available from like everywhere. Cheaper, too, since the high horsepower guys all want the bigger axles.
Bear in mind that a 5-speed OD will give you the ratios you want and make the truck more driveable than a 3-speed with tall gears.

 

Unless you're planning on having two complete chunks and swapping back and forth, you can just buy a ring and pinion set and have somebody set up the new gearset on your existing chunk.