I have a '65 F250 4x4. I'd like to convert it so that I can take it on long trips at freeway speeds. It has a 390 and power steering. I've been told that I need new axles, current axles are stock. Where to start?

 

Stock is a Dana 60 4.56:1 rear ratio and a Dana 44 4.56:1 front ratio. To change the gears in them to a lower numerical value than 4.56 you'll likely also need to change the carrier from high to low.

Axle Builder | Dana 60 Rear Axle (High or Low Carrier)

It's fairly much the same story with the Dana 44 front ends except the carrier break ratio is 3.92 and up for high or 3.73 and down for low carrier.

Front and rear needs to be fairly close ratio to one another, too, if you want to keep the option of using 4 wheel drive modes.

 

What does the warranty plate provide for an axle code? click on the link below - you could have one of three Dana rear axles codes for the 4x4 yet perhaps another axle code listed with yet another ratio. For example the 65 4x4 I have has an 08 axle code or, 3.50 on the truck.

Decode Your '65-'66 Ford Truck VIN Tag - FORDification.info - The '61-'66 Ford Picku Resource

You could possibly find a front Dana axle with a gear ratio to match or closer to your new rear axle ratio. Perhaps someone here has more information than I about the Dana front axles and can share what ratios these came with (I may have a Dana 3/4 ton 3.50 rear axle I removed from my 65F100 (previous owner installed it). The axle is sitting unused - private message me if interested).

Curious about your power steering set up. Can you share that?

tom