I have a 1990 f250 with the full floating rear axle. I have searched the archives and determined it is the same axle that is used in the f350. I am going to put a flatbed on my truck and I want it to have duals on the back. Is there a diffrence in axle width between the 250 and the 350 or is it as easy as bolting on dually wheels? If it is as easy as bolting on the dually wheels is there any diffrence in the wheel stud length or diameter?
Thanks,
Jeff

 

Dually axles are different entirely, and not just the width.

You'll also have to carry two different spares, one for each axle, unless you do something with the front to adapt it to mount dually rims.

 

How are they diffrent?
I am curious, I have read numerous posts that made me beleive that the HD f250 sterling full floating rear axle was the same as the rear axle in a f350, the posts did not specify if the f350 was a dually or not. I know the f350 has a solid axle up front instead of the dana 50 like I have now on my f250.
Thanks,
Jeff

 

when searching for rear ends, look for full floating 10.25" rear end. Forget about the F250/350 badges, it won't help. Bring your tape measure to verify spread on spring perches and overall axle width. When I swapped my axles for 4.10 axles (before installing 5.13 gears) I got them out of two different f350 trucks. The Dana 60 front came off of a dually. The only "conversion" needed was swapping the wheel rotors with the ones that were on my Dana 50 front end. It was a very forgiving undertaking. Spindles were identicle.

If you're going with a flat bed, does it matter if your wheels stick out a little further?

 

sc4x4 - I'm not trying to hijack your thread, but I'm looking to do the same thing. I have a '87 350 SRW with the full foater you're talking about. From what I've heard the dually axels are indeed shorter, and like andym said - entirely different. The differential is the same, thats about it.

I just talked to a guy that sells a whole bunch of Ford trucks - he's got his own personal junk yard - all Ford trucks.

Here's the part I'm not sure of. He said that the frames on a dually are actually narrower! 34 inches versus 38 inches for the SRW. I thought I could buy a dually rear and bolt it to my frame, requiring only from (and including) the spring hanger down. Anybody got a dually to measure? Let's get this part figured out.

 

I'm attempting to turn my '86 F-250 4x4 into a dually flatbed as we speak. I'm using an '89 F350 dually 2 wheel drive as a donor. The dually frame is in fact narrower. So are the rear springs, 2 1/2" versus 3", and the distance between the spring perches is a lot narrower. The actual axle tubes themselves are longer by about 2" on the dually. When I tried to put the dually wheel on the F250, it rubs on the spring. So now I'm trying to figure out what to do. I'm considering heavy duty bolt on wheel spacers, the kind that bolt to the hub, then your wheel bolts to the spacer, not the cheapy sandwich type spacers. Swapping the axle is almost out of the question since I'd have to weld on new perches and change the gears.

 

Thanks, Southtowns27 you probably saved me a bunch of work, and probably talked sc4x4 out of doing too.

Although if I had the whole truck I'd probably cut the frames and splice them together. I know - fire up the torches boys and let the flaming begin! But before you get to carried away about it being unsafe and all, it CAN be done safely.

I think your gears would fit, although it's better to let somebody with experience do it if you can't. What are you going to do with that dually, if you don't make the swap?