1978 axles into 1970 f-250 high boy

[mdbaker42]

So I'm gearing up for an axle swap to get disc breaks. I bought a matching pair of 1978 f-250 axles to go into my 1970 f-250 high boy. I know that 1976 through mid 77 are a direct bolt on. Could anyone give me an idea of what type of modifications I need to do to the new axles I bought, pryor to installation? The axles are dana 44 and 60. One more question. I have a stock grany set up. If i leave the same gearing of 3.54 in the new axles, how will that change the way it drives? Thanks, Mike.

[zainyD]

You're '78 axles will also bolt right in. An advantage the 78/79 F250 front axle assembly has over the 76/77 is the high-pinion (HP) differential with reverse spiral (RS) ring and pinion. This provides a better front driveshaft angle and allows for better ground clearance. Not only that, but the ring & pinion in slightly stronger.

With regard to the gear ratio, it may be a good thing because it will keep your engine's RPM range lower, especially at higher speeds. What size tires are you planning on running?

[mdbaker42]

Well, that’s good news. Sorry for the delay in getting back. Run,run,run, take a minute for me and repeat. Know what I mean? Anyway, so I read all about the 76/ mid 77. I can’t remember seeing anything about the 78. Just looking at it on the ground, everything looks the same. Still, your information just.... Smells like victory. One question I accidentally left out was the high pinion factor. Again, breathing deep. As for the tires. I’m running General, LT265/75R16. Not a big deviation from stock. Thanks zaniyD. I appreciate your support. If there’s anything else you think I should know, let’er rip. Thanks, Mike.

[zainyD]

You should be good to go. If you want to upgrade the steering, the knuckles on your axle are flat-tops, meaning, they can be used for crossover or high-steer. Sounds like you just want to get rid of the closed knuckle kingpin and drum brakes though so getting fancy with the steering is not necessary. I have a tendency to get lost in the black hole of upgrades and modifications.

As long as you have a good running motor that's properly tuned you will enjoy the lower RPM's the 3.54 gears give you. Enjoy!

[mdbaker42]

Your knowledge is appreciated. Black hole included. Thanks.

[stpackard]

You might check if your D44 has a steering arm riser block. If it doesn’t it might’ve a good idea so you can get your drag link running parallel. The steering arm is a pain to get off it has cone washers.
It is almost a direct bolt in, just did it. I redid brake lines and put the valve under the master cylinder/booster, and used a pv2 which is a disc/drum. I don’t think your stock drum/drum valve would work but I’m not sure.
Use front brake hoses from a 76 F250 because it was still a highboy (77.5-79 went low) and they’d gone to disc brakes in 76.

You’d also have to move a few shock towers around and maybe redo exhaust. I was going to use some long tube hooker headers but found they’d hit the HP drive line. Used Sanderson shorty ff427.
Did you put in power steering?