Fitment
Cab to axle: what it means and how to measure it
The one measurement that determines whether a chassis cab takes an HD-60 or HD-60-HC, how to measure it, and what happens if you get it wrong.
By Aluma Tray TeamUpdated 4 min read
Cab to axle, usually written CA, is the distance from the back of the cab to the center of the rear axle. On a chassis cab it is the number that decides what body fits.
Why it matters more than bed length
A chassis cab does not come with a bed, so there is no bed length to go by. The frame behind the cab is what you are mounting to, and cab to axle tells you how much of it you have and where the axle sits under it.
Get it wrong and the weight lands in the wrong place relative to the axle. That changes how the truck handles and how load is distributed, and no amount of tie down hardware fixes it.
What Aluma Tray builds for
The HD-60 and the HD-60-HC are both built for domestic commercial 60 inch cab to axle truck chassis. Fit kits for the HD-60 are made for 60 inch CA North American trucks only.
Eighty four inch cab to axle is the next one up, and the HD-84 is being built for it now. It is still in development as the 2027 model, so there is no price, weight or load rating to quote yet. If that is the chassis you run, tell us and we will let you know when the specs are signed off.
Unlike the 6.75' and 8', which mount to factory locations on the frame, the HD-60 and HD-60-HC mount to dealer drilled and mounted locations. That is normal for a chassis cab body, and it is one reason these builds go through a dealer or the factory rather than a driveway install.
How to measure it
- Park on level ground with the truck unloaded.
- Find the back face of the cab, not the back of the mirror or a body moulding.
- Measure straight back along the frame to the center of the rear axle hub.
- On a dually, use the center of the axle, not the center of the tire pair.
- Check your result against the manufacturer's published CA for your model and wheelbase.
If your truck is not a 60 inch CA
Talk to us before ordering. Do not assume a nearby measurement is close enough, and do not order a tray on the expectation that it can be adapted. Send your truck's year, model, wheelbase and CA and we will tell you plainly whether we have a fit kit for it.
