Well it's been quite some time since I've been on here but I have questions and hoping to get answers. I've searched and I'm pretty sure it may work lol. I have access to a complete 06 F550 frame and running gear. I've measured the frame rails and it is the same width as my excursion. Has anyone done it? Anyone have info on why it will or will not work. Been wanting to make this thing a dually and if I can make the 550 stuff work then cool I'm going to do it.

Let me know

 

I thought that the chassis cab trucks, like the F-550s had the narrower frames behind the cabs compared to the pickups that the EX frame is more similar to.

 

That's what I was thinking also. I'm going to go measure the total width. My understanding is this is a 37 inch wide frame 550. It was a very short truck to begin with. It looks to have the wheel base of a regular cab long bed.

 

I think the shortest F-550 would be the 60” cab to axle vs the longbed pickups at 56”/57” cab to axle.
How many leaves in total are in the rear leaf pack of the 550? If you leave them all in place it will ride very rough because…………F-550.

 

A dually Excursion,,, that'd be interesting for sure, rear dually fenders would be a challenge considering how close the rear door is the the wheel well opening.
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I didn't think to count them. But I was thinking about that. I don't have the frame in my possession atm but hopefully in the next couple days or so I'll be able to get it

 

The number of leaves (11) of the F-550 spring pack doesn't matter, because the eyelet to eyelet distance of the F-550 leaf springs isn't long enough to reach the riveted spring hangars on the Excursion frame, which itself is also wider than the F-550 frame, by several inches, so the rear axle spring perches of the F-550 axle would likewise be too narrow for the Excursion.

The frames are nominally the same width at the front axle and under the cowl, but the chassis cab frames taper inward under the latter half of the cab, in order to conform to the NTEA truck frame width standard for universal application of vocational truck bodies. But none of this matters either, since the F-550 rear springs simply are not long enough to reach the Excursion spring mounts.

 

Not to mention it would ride like an empty school bus.

 

There are pics of F650 and few 550 excursions floating around out there, so something like this has been done by grafting the ex body parts into the F series.
I know nothing about it other than it would be a very cool project.

 

Y2KW57 .. thats the info I'm looking for. I had heard the 550 eyelet lenght was different but I don't have the springs in front of me to get those measurements. As for the width from rail to rail that is easy to deal with as long as there's room to move the perches to the outside. Hopefully I can get started on this soon.

 

F-550 rear leaf springs are ~ 55.x"
Excursion rear leaf springs are ~ 57.x"

The 2006 F-550 rear axle has a banjo style housing with a drop in third member of carrier and differential. The banjo housing has box formed tubing and a welded on rear cover. The formation of the boxed portion of the tubing does not span the entire axle width. What is readily observable to most is how the box tube tapers in the vertical plane inboard to form the oval in the center that holds the carrier.

However, what isn't as easily noticed is that the box tubing tapers in both the vertical and horizontal planes almost immediately outboard of the spring perches to change shape from a square tube into a round tube that holds the wheel bearings, hub, and brake rotor. In other words, the cross-sectional dimension between the spring perch and the brake backing plate flange is not the same as the cross-sectional area beneath the spring perch and inboard of the spring perch prior to the housing's expansion in the vertical plane.

The pics of the F-650 Excursions mentioned by callforfire are exactly as he described, where the Excursion body is grafted onto the F-650 frame, not the other way around.

 

Well I think that pretty much sums that up. I didn't know the the shape changed on the housing of those axles. I looked for info on those axles and never found that. I really appreciate the info. This whole thing got started with wanting to do the 06-07 250 front frame section to switch over to the d60 and coil springs in the front with the matching rear. Then I found the 550 stuff and thought man that would be awesome lol. So guess it's back to the original plan. Thanks again man