Regular truck vs Chassis Cab Frame


Active member
I can't for life of me find the thread where someone mentioned a difference in the frames of these two types of vehicles. One I believe was a box frame, more rigid say, than the other.

I was wondering if this also applies to the E-Series or Express Vans vs Cutaways of those vehicles.



Active member
So I see now, in searching this there is a third option.

Regular Truck or Regular Truck Box Delete vs Chassis cab.

Is there a way to tell which is which when looking at a flatbed? I doubt these used car guys will know.


Cab chassis trucks have frames that are straight and flat from the cab back which makes them easy for upfitters to build their products on. Regular pickup truck frames are usually not flat or straight to snake around the rear axle. Most car salespeople would not know this.


Kodiak Wrangler
If it was shipped from the manufacturer as a chassis cab it will have an incomplete sticker on the door

and then hopefully a 'completed' sticker by who finished (installed the flatbed, etc) it.


Well-known member
This guy likes to put a positive spin on production line RV's which I don't agree with but some of his other content is good.



I was going to mention the incomplete sticker also, if you can get ahold of the window sticker that came with the truck it will list if it is a cab/chassis.


Well-known member
The links below are for 2021 F-350/450 pickup trucks (including box delete pickup trucks) and F-350/450/550 chassis cabs, but I think the information applies to 2017+.

From Ford's link about Super Duty pickup trucks:

"The fully boxed frame, built of percent high-strength steel with up to 10 crossmembers, is 24 times stiffer than the previous design. The frame is designed to minimize flexing and twisting while maximizing strength and torsional rigidity, and serves as the foundation for the impressive towing and hauling capability of the Super Duty® ." See:

From Ford's link about chassis cab trucks:

"The chassis cabs have a fully boxed frame under-cab with C -channel aft-of-cab frame." See:

Some chassis cabs can be ordered with aft-axle frame extensions. These can be useful for supporting longer boxes while keeping the wheelbase short for an improved turning radius (compared to a longer wheelbase for the same length box).

Flatbeds are available for pickup trucks and chassis cabs, but, because of the difference in frame shapes, aren't interchangeable.


Is there a way to tell which is which when looking at a flatbed? I doubt these used car guys will know.
Look at the frame. The boxed frame rails are rectangular tubes. Open C are C channel with the mouth facing the centerline.

Ford went to a fully boxed frame in 2017 for F250 and 350. Chassis-cab and all F450s and F550s are open C.

Other manufacturers? Not sure.


Chassis Cabs are going to be 60" (and they come longer) from the rear of the cab to the centerline of the rear axle--usually called cab-to-axle or CA. Pickups will be around 56-58" depending on the brand. The 60" is standardized so aftermarket bodies will fit with regards to the rear wheel opening. CC's have a 1.5 to 2" narrower rear axle than a dually pickup.


The industry standard spacing for frame rails on a cab & chassis frame is 34". Pick ups and box deletes have frame rail spacing all over the map, generally wider than 34".


Western Dirt Rat
Bringing this back up. The primary easily identifiable feature of the chassis cab is the straight frame from cab to end of frame. Frame rails will be narrower on a C/C than a bed delete (34"). Bed delete will have humps in the frame at the rear axle (ie, not flat) and the rails will be 37 to 38 inches wide. Pretty easy to see these features on a flatbed. Some flatbeds come with adjustable long sills for mounting on either style.


Active member
Another difference at least on Ford F-350 is that the chassis cab has the gas tank in the rear, while the bed delete has the tank in the middle with space to mount a spare tire under the rear.


Builder of Things That Interest Me
I found that the rear leaf springs are different on my 2008 F350 cab and chassis. Not sure about other years but it's worth checking if you want to add aftermarket lift springs.


Here are a couple pics of my C&C's. First id a 2021 Ram 5500 I ordered with 60 inch CA and dual tanks. Second is 2018 Ram 5500 with 84 CA I put a switch N go bed on. I can have dump or flat bed.IMG_4027.jpgIMG_2569.jpg