Hey everyone, I have a 66 f-250 that I would like to convert to a 4X4. What is the best way to go about this? I saw in the shop manual that a version had the coil springs in the front like in the 2x4, I'm not sure if it was a 100, 250, or f-350. Is it possible to still use my original frame and find a front axle that will sit under it ? I have no idea how difficult it would be or what to look for but its an idea and I'd like to see what the Pros think and get ideas as to how I can do this conversion in the future . It currently has a 352 under the hood with a np435 tranny and a dana 60 rear with 4.10 gears.

Thanks- Henry's66

 

The 1966 F100 4x4 used coil front springs. It's the only one in the 1961-1966 lineup to be both 4x4 and use coil springs. But the setup is quite different than the 2WD trucks with the twin-I-beam and coil springs. You'd first want to eliminate the entire front carrier member for the I-beams by cutting it out similar to if you were doing a Crown-vic suspension swap on it. Then you'd have to decide if you want to try to engineer something to use coil springs or if you want to use leaf springs in front. There is also the need for a front axle with a gear ratio in the 4.09 to 4.11 range to match the 4.10 rear closely. A transfer case and way to mount it behind the transmission - probably a divorced NP205 or Dana 24 - although they did make a married transfer case but that would require a different output housing on the NP435. You'd have to shorten the driveshaft you have and have one made for the front as well as a short coupling shaft if using a divorced transfer case. A shift lever for the transfer case - and how to mount the lever since your 2WD NP435 has no connection points from the factory for a transfer case shift lever. Overall a lot of work but can be done. @53deere has a 1966 f100 2WD that he converted to 4x4 by using the front member from a 1978 F150 4x4 that allowed him to use coil springs. A neat solution. Lots of pictures to look through that might give some ideas.

1966 F100 Short-bed 4x4 Build - Ford Truck Enthusiasts Forums (ford-trucks.com)

 

Back in the late ‘90s/early 2000s, I had the same question for my ‘65 F-250 and posted here. They told me back then about the easiest options were to either just find and buy a 4x4 truck; or find a rolling 4x4 chassis from a little newer 4x4 F-250, and just put my cab & bed on it. In a nutshell I went with option one and now have a ‘66 F-100 4x4. Of course, eventually being “relieved” of my F-250 made that choice a little easier for me personally.

 

Thanks, I'll take a look at them.
Edit: That was great, its a f-100 in the photo but I wounder if I can find an 8 lug front end for this future conversion, cutting and welding is a little scary I'll admit but it is do able as shown. Does any one know why the f100 only had the coil spring front? it seems like an interesting concept but why does no one ever use it for the larger f- series trucks?
very interesting Thanks Again- Henry's66

 

What the others said is good advice. A lot depends on your skill level and what you can find or afford to do the conversion. The easiest would be to swap your body over to a newer F250 4x4 chassis. 67 through 76 used the FE engine so your 352 should match the existing engine mounts on the frame. Mid 70s gets you disc brakes and power assist steering though not the best steering system especially old and worn. Up to mid 77 is just like the 76 except no FE engine. 67 to 77.5 is still a 34” frame width all the way to the back and has a divorced transfer case. Wheelbase will need to be shortened a few inches but relatively easy with the straight 34” frame.
77.5 through 79. Better power steering, front disc brakes, integral transfer case, really a better chassis but the frame flairs out to a wider width in the back and a bigger hump over the rear axle cause issues.
1980 started the TTB trucks, I wouldn’t go that route.