No Verified Fit Yet? How to Measure Your Apparatus Fuel Filler

We publish a fit when there is a verified fitment record behind it, and we do not publish one when there is not. That means some platforms departments ask about regularly are listed on our fitment matrix as needing measurement rather than as verified.

The two that come up most are the Freightliner M2 106 and the International CV. Both are used under apparatus and larger command builds. Neither has a verified record on file today.

Why We Will Not Just Tell You It Fits

Because the honest answer is that we do not know yet, and the cost of being wrong lands on you. A door that does not sit flat on the body panel is not a door — it is a part that has to come back off, on a rig that needs to be in service, after somebody already drilled into the body.

There is also a real reason fitment is not predictable from a chassis name. On these platforms the fuel filler is completed by the body builder, and apparatus bodies are not standardized the way a pickup bed is. Two rigs on the same chassis, same year, from two builders can present completely different surfaces around the same filler neck.

So we measure. It is not a stalling tactic; it is the only way to give you an answer that holds.

What to Send

Photos — four of them

• Straight on at the filler, square to the body panel, close enough that the opening fills most of the frame
• From an angle, so we can see how much the area is recessed and whether the surrounding surface is flat or curved
• Stepped back, far enough to show the filler in the context of the body panel, compartments and any hardware near it
• With a tape measure in frame across the opening, which lets us sanity-check every other number you send

Measurements — five numbers

1. Filler opening diameter. The opening itself, not the cap.
2. Flat surface around the opening, measured both vertically and horizontally out from the edge. This is the number that most often decides the answer, because the door needs a flat area to seat and fasten against.
3. Recess depth, if the filler sits in a pan or pocket, from the body surface to the base of the recess.
4. Distance to the nearest obstruction — a compartment door edge, hinge, latch, light, handrail, ladder mount or body seam. Anything that would foul a door as it swings.
5. Swing clearance. Which direction there is room for a door to open, and how much.

Details about the rig

Chassis make, model and year. Body builder if you know it. Whether it is diesel, and whether there is a separate exposed DEF filler. Whether the rig has more than one fuel filler — dual-tank builds need one door per opening. And whether a non-locking factory or builder plastic trim door is currently in place, since that comes off and the locking door takes its position.

Two Things That Make Measurements Useless

First, measuring the cap instead of the opening. The cap diameter tells us very little; the opening and the surface around it tell us everything.

Second, measuring a different rig than the one you are ordering for. If your fleet has several years or several body builders, measure each combination. Remounted units are the ones that catch people out, because the body has lived on more than one chassis.

What Happens Next

Send it all through the contact form. We will compare it against the doors and bezels we actually have and give you one of three straight answers: an existing door fits, an existing door fits with a specific caveat you should know about, or nothing we make fits your rig properly.

That third answer is a real possibility and we will say it. A department that hears "no" from us keeps its money and its bodywork intact, and that is a better outcome than a sale we had to talk ourselves into.

If your platform is already on file — the Ford E-350 and E-450 cutaways, the F-53, the Super Duty chassis cab family, or the Ram 5500 — you do not need any of this. Look it up in the fitment matrix or start from Find My Fit.