If you are speccing a crane truck, the single decision that drives everything else is the chassis. The Ford F-450 and F-550 cab & chassis look nearly identical on the lot, share the same 6.7L Power Stroke, and take many of the same bodies — but they are not interchangeable once a crane and outriggers are bolted on. Here is how we spec them for real Texas service and oilfield work.

The short answer

Under a 4,000–6,000 lb crane with a 9–11 ft service body, the F-550 is the right chassis almost every time. The F-450 makes sense when your crane is 3,200 lb capacity or less, you are running a shorter body, and you want a truck that drives and parks more like a pickup. Buying an F-450 and then hanging a big crane off the back is the most common and most expensive mistake we see.

Spec comparison (2025–2026 cab & chassis)

Spec	F-450 Cab & Chassis	F-550 Cab & Chassis
GVWR	~14,000 lb	~18,000–19,500 lb
Rear axle	DRW	DRW, heavier rating
Typical chassis weight	Lighter frame & suspension	Heavier frame, springs, brakes
Available CA lengths	60″, 84″, 120″	60″, 84″, 108″, 120″, 156″, 192″
Realistic body + payload budget	~5,500–6,500 lb	~9,000–11,000 lb
Practical crane range	Up to ~3,200 lb	4,000–7,500 lb+
Best body length	9 ft	11 ft – 14 ft
Max towing (properly equipped)	~19,000–21,000 lb	~21,000–24,500 lb

Why crane weight eats an F-450 alive

A crane is not just its own weight. It brings a reinforced subframe, outriggers, a compressor or welder in a lot of builds, hydraulic tank and oil, plus the tooling and materials your crew actually carries. On a 4,000 lb-capacity crane build, the crane package alone is commonly 1,800–2,600 lb installed. Add a steel crane body at 2,200–3,000 lb and you have consumed most of an F-450’s available payload before a single wrench goes in a compartment.

Rated crane capacity also assumes the chassis is stable. That is why crane manufacturers publish minimum chassis requirements — frame section modulus, resisting bending moment, and wheelbase. The F-550’s frame and rear axle rating are what let you legally and safely use the crane’s full chart at extended reach.

Cab-to-axle: the number to get right

CA is the distance from the back of the cab to the center of the rear axle, and it dictates body length. Rules of thumb we use daily:

• 60″ CA — 9 ft body. Tight jobsites, light crane or no crane.
• 84″ CA — 11 ft body. The sweet spot for an F-550 crane/mechanics truck.
• 108″–120″ CA — 12–14 ft body. Bigger crane, more compartment volume, room for a lube skid or air package.
• Leave room behind the axle for the crane’s mounting position — a rear-mount crane wants weight distribution checked front-to-rear, not just total GVWR.

Which bodies fit each chassis

We build F-450 crane trucks most often on RKI truck bodies and CM service bodies in 9 ft, and F-550 builds on 11 ft steel service bodies with a crane-ready compartment layout. If your work is hauling and light lifting rather than true crane work, a skirted flatbed from Norstar or Bedrock with a bolt-on davit is far cheaper. See our crane bodies and service bodies pages for the full lineup.

Cost and operating differences

An F-550 chassis typically runs a few thousand dollars more than a comparable F-450, and you will notice slightly stiffer unladen ride and a wider turning circle at the longer CA lengths. In exchange you get headroom — headroom that keeps you legal at the scale, keeps the crane inside its stability chart, and keeps you from replacing the truck in two years when the job outgrows it. If your crane spec is anywhere near the middle of the range, buy the F-550.

Get a Real Quote — Installed, Not Estimated

Bring us the crane chart and we will confirm the chassis before you order. Star Truck Equipment is at 2507 County Rd 231 in Wharton, TX, about an hour southwest of Houston. We stock beds and bodies from Bedrock, CM, Norstar, NXG, Pronghorn and RKI, and most in-stock installs are done in one business day. Call (979) 532-1486 with your year, make, model, cab-to-axle and wheel setup and we’ll tell you exactly what fits and what it costs installed — or browse current inventory.