Chassis Cab frame vs "Regular" truck frame
The reason why some frame mounted accessories like towing equipment that fits pick up frames but does not fit Chassis Cab frames is due in part to the difference in width between the frame rails. Pickup frames are more or less 37" apart at the vertical web, while Chassis Cabs conform to the common NTEA standard of 34" width between the vertical webs of the frame rails. The 34" spacing is common to most brands of commercial truck chassis frames, from Peterbilt to KW to Hino to Isuzu to International to Freightliner to the F-650/750 and the F-450/550.
Ford makes two versions of F-350 without a pickup bed. The first version is called a "box delete", and while it may look like a chassis cab because it doesn't have a bed, it actually has the same frame as the pickup, otherwise referred to as a "wide frame". And this is where it could get confusing, because Ford also makes an F-350 without a pickup bed in a "narrow frame" version, and this would be considered a true "chassis cab", with a frame designed to accept universal vocational bodies that could be equally fitted to a variety of truck brands.
The universal fit is possible due to the National Truck Equipment Association's efforts many years ago to encourage chassis manufacturers to abide by certain common measurements to enable vocational body manufacturers to build one type of service body, dump body, flat bed, fire apparatus body, etc that could be mounted to a variety of truck brands with relatively equal ease of fitment.
Pickup frames typically have an arching hump over the rear axle, which helps increase the range of suspension travel between empty and loaded, as there is expected to be a greater day to day variability in owner operation between empty and loaded states, and, pickup buyers place a higher value on ride comfort in either state.
Chassis cab frames typically have flat straight frame rails, for ease of vocational body equipment mounting. But there are more differences than just the shape and width of the frame rails. There is also a commonized cab to axle distance in Chassis Cabs that differs from pickups. For example, the F-350 "box delete" option that only looks like a chassis cab, but isn't... uses a wide frame that will have a 56" cab to axle distance. By contrast, the true and genuine F-350 "Chassis Cab" will have a 60" cab to axle distance (or an 84" CA, depending on the number of doors in the cab).
All of this matters when it comes to buying shock absorbers, which was your original quest and reason for the question. The F-350 pickup, and the F-350 box delete wide frame, both use the same humped frame with only a midship fuel tank and a rear frame mounted spare tire aft of axle. These frames also have staggered shock absorbers in the rear, where the driver's side shock angles rearward, and the passenger side shock angles forward.
By contrast, the rear shock arrangement of the narrow frame chassis cab has BOTH shocks angling forward, as there is an aft axle fuel tank on the narrow frame that isn't available on the wide frame. There are also spring rate differences, drive shaft differences (ie single vs double cardan joints, etc) and suspension travel differences that when considered in combination may warrant a different shock valving. But the most tangible difference that you can actually see is the shock mounting differentiation between pickup frames vs chassis cab frames.
If your F-350 has or had a pickup bed, then it is a wide frame, and therefore anything listed for an F-350, except or excluding chassis cabs, should fit fine for you.
If you’re considering a cab chassis truck, know you’ll need a ‘commercial’ insurance policy and it will be a ‘stated value’ policy because commercial vehicles are not listed in blue book, etc.
This truck has 460k miles on it now and I’ve had it since 2003.
@Brandonpdx , how do you like that "airless" "air" hitch?
Do you hot shot from Oregon to Indiana without a sleeper?
How do you deal with HOS?

My truck rides pretty good at close to 10k lbs ‘empty’. It’s really nice full of fuel rolling closer to 11.5k lbs.

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@Brandonpdx , how do you like that "airless" "air" hitch?
Do you hot shot from Oregon to Indiana without a sleeper?
How do you deal with HOS?
I dont run over the road right now but I was last summer back and forth between WA and IN. Right now I just run local doing factory pickups...nothing more than 40 miles in any direction. Over the road I had to fill out a logbook sheet and follow the time rules. I slept in the truck. It’s a hoot during the warmer months.
Is the standard (‘99-04) DRW wider hub-to-hub than a cab chassis?
How much wider is cab chassis rear axle than ‘99-04 SRW F250/350?
Hub to Hub:
F-350 DRW wide frame pickup rear axle hub to hub = 74"
F-350 DRW narrow frame chassis cab rear axle hub to hub = 71"
Tire to Tire:
F-350 DRW wide frame pickup rear axle outside tire to outside with stock LT235/85R16E tires = 94.7"
F-350 DRW narrow frame chassis cab rear axle outside tire to outside tire with stock LT215/85R16E tires = 90.7"
F-350 DRW narrow frame chassis cab rear axle outside tire to outside tire with stock LT235/85R16E tires = 91.7"

I seem to recall you ‘could’ possibly use the standard wide DRW on a cab chassis if you moved perches, etc but a cab chassis axle on standard F350 the tires would hit the leafs if you moved the perches out.












