That must be why the other guys went to so much trouble to take the chevy parts and adapt them to make the f150 axle 8 lug. Otherwise, if the f250 ttb axle was the same as the f150 ttb axle, they could have just swapped in a f250 ttb axle. I think in the article I read, they were putting 8 lug wheels on a Bronco.

So, unless someone finds out different, so far we have confirmed the f250 ttb leaf spring axle will not interchange(bolt in) where a f150 ttb and a f250 2wd coil spring frontend was originally.

Let me do a little summary of what started all this and see if I get it right.

We have a good 86 f250 diesel 2wd extended cab pickup.

We have a 85 f250 diesel 4wd regular cab pickup that can be picked up cheap(bad body).

The desire is to use the cheap pickup to convert the 86 to 2wd.

There have been several different options put forth to handle it, but I don't see any easy ones. I would say swap the frames, but the frame and wheel base is different between the regular cab and extended cab isn't it?

 

Yes... can't swap the frame.

 

That should read "The desire is to use the cheap pickup to convert the 86 to 4wd.

I knew I wouldn't get it right.

 

Swapping to a leaf sprung solid axle isnt all that hard. Here are some pics of what some FSB guys did. You can go check out their Solid Axle Swap (SAS) forum, and check out the "Ultimate SAS project source" sticky thread for a list of builds people did along with links to their threads with pics and info...but here are a couple pics to get you started:


..and another guy

 

If that would work for an SFA, I can't see why it wouldn't work just as well for a leaf sprung TTB.

Sticking with the original idea might not be as difficult as it would at first appear. Seems to me that it wouldn't be too hard to cut two 3/4" thick spacers for each side out of .25" wall DOM tubing with an ID slightly larger than the diameter of the bolts that hold the radius arms to the TTB beam. One spacer on top and one on bottom of the TTB housing and VIOLA' - they make up the 1.5" difference in the height of the two axle housings to make the radius arms fit. If you wanted to get a little fancier and make it even stronger, you could even weld the spacers to the top & bottom surfaces of the F250 TTB.

Soiv, my apologies for doubting you. If the space between the u-bolts is 4" then the height of the housing indeed must be right at 4" as well - the pictures don't lie. Still doesn't make sense to me that the F250 TTB housing is smaller than the F150 TTB housing - but that's the way it is. Maybe it is to give the radius arms more leverage to prevent axle wrap of the coil-sprung axle housing. Looking at the thickness of those leaf packs I don't think axle wrap would be much of an issue on that F250 TTB....

Anyway, I think that with only minor mods, the F150 radius arms can still be made to fit the F250 TTB fairly easily. It would sure take a LOT less fab work than the SFA swap....

 

that could work.
You could convert the 3/4 ton to coil sprung a few different ways....you could also get some shims to weld onto the radius arm to make it stronger, and mount directly onto the I-beam.

 

Thought about that too. There are 3 reasons why I think the spacers would be a better approach.....

1) You wouldn't have to drill a 1/2" or 5/8" hole through an inch and a half of steel for the bolts that mount the radius arms to the housing - like you would with the shims. That's a lot of drilling.
2) The 3/4" spacers cut out of 1/4" wall DOM tubing would take about 5 minutes apiece to make with my chop saw or bandsaw. Shims to weld into the radius arms would be much more complicated pieces to shape.
3) By welding the spacers to the TTB you would end up with the anti-wrap leverage action of the taller 5" axle housing height ~ 2.75" both above and below centerline of the axle. I strongly suspect that is why the radius arm axle is 1.5 inches "taller" than the leaf sprung axle to begin with - for the anti-wrap benefits.....

 

well I am looking forward to the results

 

Update on my situation;

I went to the auction, and stuff was selling a lot higher than I expected. Most were early and mid 90's chevy trucks. A lot of them were diesel. One truck went through and it was stated "No oil pressure", and it brought $1200.00. A couple others were "will not shift", "will not run"(they got it running though) and they all brought $1200-$1600 in the auction.

So I was not surprised the only Ford pickup in the bunch brought $1900.00. I was willing to pay up to $1000 for it. It was a 88 f250HD, automatic, 4.9 fuel injected with A/C. The A/C had a tag where it was converted to 134a, and looked like it probably worked. Looking underneath, I could tell the engine had a major oil leak somewhere, and the frame had surface rust, but was not flakey rust.

After this long drawn out thread, some of you are thinking what is the point of going to the trouble to convert a 2wd to a 4wd? If you were there looking at this truck at the auction, you could tell right away. The body was beautiful The paint was faded badly, but no rust out in the cab corners, under the doors, over the wheel wells, under the taillights. And most 4wd I have seen, the driver's side seat is always crushed and sagging on the corner. This one was perfect.

 

i bought a 86 f250 4x4 truck that had a 6.9 with a manual tranny in it for 400 dollars. i got the bg 1345 transfer case and and drive shafts with it. there was no engine, tranny, no hood, no doors, no streeing wheel, and no seat in it. i bought is thinking i could take my 81 f250 2wd 400 c6 and just drop it in this 86. i learned in the making that there was a lot of mods to make in wiring, and engine stands to get a gas to set where a diesel once set.
also a few other things on the front end. i believe they make two diffent 44 ttb. you got the reg dana 44 and th dana hd44, but also in the 70's trucks they used a solid axle with coil springs stands. from my understanding there is a little mods in relocating the spring brackets. i dont know if this has been thought of.
also if i recall right you have to put at least a 2" lift on the truck to fit a straight axle under a ttb fram.