4x4 Conversion/Swap megathread

After a couple hours of research on swapping my 2wd 84 to a D55 or D60, and finding bits of info on what frames had this/that/the other, I wanted to call upon the members here to help me get everything straight and maybe create a new documentation page.


Below is the summed up information from the rest of the thread up to now (11/28/20):

There are no 4x4 D60 trucks before 85.5

Only 1986-1997 F350 4x4 trucks have the holes for the track bar bracket; prior to that the 350's came with a TTB setup like the 250 models.

The 4x4 models have boxed front frame sections, so the inside of the frame rail is flat.
2wd drive models had coil springs and not leaves so they don't have shackle brackets front or rear of the axle.

There's a cut out in the 4x4 3/4 and 1 ton frames for the shackle hanger, and on the side of the frame there is a round recess stamped in for the shackle bolt, the recessed section acting as a "spacer" for the shackle.

On 3/4 ton and 1 ton trucks, 4x4 frames and 4x2 frames are different in that they do not share any mounting holes. There isn't a single hole that lines up if you're trying to put the 4x4 stuff on the front of a 4x2 frame. Only the 1/2 ton trucks have all of the same holes up front.

On the leaf sprung 4x4 trucks, there is a frame support on the passenger side frame rail by the radiator support. This is absent on the 4x2 trucks.

The solid axle trucks use a different pinion arm on the steering box.

There are numerous crossmembers used on these trucks, and they're dependent on the transmission and even the year of truck.

Stock bumper fits, but you have to grind off all of the tabs on the bottom edge of the bumper, and clearance the pre-existing notches for the stock spring eyes. Otherwise, the tabs make contact with the cross-bar on the RSK.

Rule of thumb for max lift on the stock D60 pitman arm is around 4"; anything more and you're pushing its limits to keep proper geometry. An RSK alone adds around 2" and anything above 6" total lift would probably be advised to look into crossover steering, even with the drop pitman arm.



My goal is still to make this a thread for me and all the others that want to swap their duallys or single wheel trucks. I'll periodically update this post with any more information I see added below, that way if the question is asked, there will be a one-size-fits-most thread. Hopefully I'll find a bit more information on the 1/2 and 3/4 ton trucks as time goes on.

Thanks all!

JunkCollector wrote

So far I think I've found out:

There are no 4x4 D60 trucks before 85.5?

Correct

The 84 frames don't have holes for the track bar bracket?

Only 1986-1997 F350 4x4 trucks have the holes for the track bar bracket

There's a flat area on a 2wd where there's a curve in the 4x4 frame somewhere?

Not exactly sure where that came from, but there's a cut out in the 4x4 3/4 and 1 ton frames for the shackle hanger, and on the side of the frame there is a round recess stamped in for the shackle bolt, the recessed section acting as a "spacer" for the shackle.

Some say a D60 won't fit under a bullnose without an aftermarket bumper, but I've seen it done already?

That's incorrect info.

I've seen a lot of debate on the RSK kit. There's also a "2wd to 4wd swap" kit for an OBS with bolt-in frame boxing brackets found here:
https://cpaddict.com/2wd-to-4wd-conversion-kit-for-obs-dana-60-axle/
I haven't seen anyone use this kit at all yet! Will it even fit a bullnose? Or just the 92-97 "OBS"?

I have not seen that kit used on a bullnose yet. It may work, but would probably have to be modified to work on a bullnose.

To add further, when it comes to 3/4 ton and 1 ton trucks, 4x4 frames and 4x2 frames are different in that they do not share any mounting holes. There isn't a single hole that lines up if you're trying to put the 4x4 stuff on the front of a 4x2 frame. Only the 1/2 ton trucks have all of the same holes up front.

On the leaf sprung 4x4 trucks, there is a frame support on the passenger side frame rail by the radiator support. This is absent on the 4x2 trucks.

The solid axle trucks use a different pinion arm on the steering box.

There are numerous crossmembers used on these trucks, and they're dependent on the transmission and even the year of truck. Ford seemed to change them every few years so that can make sourcing the correct one a little difficult.

I will let Shaun* and Gary address your direct questions about the SKY kit but can probably fill in some of your questions.

D60 straight axle was a running change during the '85 model year.
Prior to that the 350's came with a TTB setup like the 250 models.

No, in '84 there was no straight axle, so there was no track bar bracket needed on the crossmember.

The 4x4 models have boxed front frame sections, so the inside of the frame rail is flat.
2wd drive models had coil springs and not leaves so they don't have shackle brackets front or rear of the axle.

I don't think there's any problem fitting a stock bumper.
With the SKY superduty RSK you will have to notch the lower edge of the bumper to clear the front spring eyes.

I think you two have done a good job answering the questions.  The only thing I can add is that while I'm not running a stock bumper, I am running a bumper that bolts into the stock holes, and I'm pretty sure a stock bumper would bolt on.

Stock bumper fits, but you have to grind off all of the tabs on the bottom edge of the bumper, and clearance the pre-existing notches for the stock spring eyes. Otherwise, the tabs make contact with the cross-bar on the RSK. I should probably yank my bumper and highlight what I cut so that other people can use it for reference. I'll work on that this week.

Shaun, do you know how much lift you have to AAA the stock 350 pitman arm for a drop pitman arm to keep the steering geometry right?

I've heard 4" and I've heard 6, but since my truck isn't lifted I don't have any hands on experience.  

Rule of thumb I've always seen is 4". There are probably people who try to get away without it at 4, and they may be okay, but it depends on your springs and whether you're running an RSK. I'm in dangerous territory with my truck as the RSK adds 2", and my springs are at least 2", but I feel they're closer to 3" lift springs. That would put me at 5" of lift. Once you start getting to 6" lifts and above, the drop pitman arms probably aren't even enough and you will need to look into crossover steering.

Thank you all for your responses, you answered every question I had, but now I have a couple more (sorry!) When it comes to the drop pitman arm, are we talking lift from the stock D60 height, or lift from the stock 2wd height? I know the 4x4 trucks require a different arm to start with, which is why I'm somewhat lost.

Edit: after doing some re-reading, I understand everything now. Just took a few minutes for my caveman brain to make sense of everything

Howdy everyone! Considering another build project. Potentially another Bullnose.

Curious if anyone on the site has done a 2x4 to 4x4 swap and shared it here on the site somewhere? I'd love to see some pictures and process if it's out there. Found a few YouTube videos out there but I am a big advocate of gathering all the intel you can before you leap.

I have a few "decent" trucks in the area (mostly all 2wd).

I am not opposed of snagging one as far south as NC to try and beat the rust clock. But I most definitely want to have a 4X4 capable truck once she hits the road.

Good luck out there peeling those onions and be safe wrenching.

And thanks for taking the time to share your journeys on the site!!  

Hello, Jamie!

I think there have been several 2wd to 4wd conversions, but I don’t know if they’ve been set out as separate threads or just part of a build thread. But from my understanding on a half-ton truck it is an easy bolt-on swap. Buy two trucks, do the swap, and sell the left-over one. Not true though on the heavier trucks as the 2wd and 4wd frames are different.