Cab to axle: the one measurement that decides which bed fits

More truck bed orders go wrong on this than on anything else, and it is entirely avoidable. Cab to axle is the number that decides which body will sit correctly on your chassis.

What it is

Cab to axle, usually written CA, is the distance from the back of the cab to the centre of the rear axle. On a dual rear axle truck it is measured to the centre point between the two.

That is it. One measurement, taken along the frame.

Why it matters more than bed length

A body has to be positioned so its weight sits correctly relative to the rear axle. Too far back and you unload the front end and overhang badly. Too far forward and it fouls the cab.

Bed length describes the box currently on the truck. Wheelbase describes front axle to rear axle. Neither tells a body builder where your rear axle sits relative to the back of your cab, which is the thing that matters.

The common values

Most one ton and heavier chassis come in a handful of CA lengths, commonly 56, 60 and 84 inches, with others in between depending on the manufacturer and the configuration. Service bodies and flatbeds are built to suit those.

Do not assume yours from the year and model. Trucks are ordered with different configurations and a chassis cab is not the same as a pickup that has had its bed removed.

How to measure it

Park on level ground. Measure along the frame rail, not along the body, from the back face of the cab to the centre of the rear wheel. Use the wheel centre as your axle centre; it is close enough for selection purposes.

Write the number down and photograph the truck from the side with the tape in shot. If you send us that photograph we can sanity check it, and we would rather do that than have a body arrive that does not sit right.

The other things we need

Single or dual rear wheel. Dual wheel chassis need a wider body. They are not interchangeable and this is the second most common mistake.

Frame width, which is usually standard within a manufacturer but worth confirming.

Whether you tow gooseneck, because a gooseneck ball set into the deck is not a small retrofit.

With CA, wheel configuration and your towing answer, we can tell you exactly which bodies fit.

Plan the fit out before you buy

Headache rack, underbody boxes, a crane or hoist, beacons and work lighting all change what body you should be buying. A body rated for a crane is not the same as one that is not, and adding one later is not always possible.

Think about the wiring route while the body is off the truck, because that is the only easy time to do it.

Fitting

Bodies mount to the frame with brackets and U bolts. The factory bed comes off, lighting and wiring transfer across, and the new body is squared and torqued. It is a workshop job rather than a driveway job, and most people have an upfitter do it. Budget for that when you price the body.