Yes. The RV Fuel Vault fits Dynamax Super C motorhomes — including the Isata 6, Force HD, and DX3 on the Ford chassis and the Isata 5 on the Ram 5500 — securing both the diesel and DEF caps.
Which Dynamax models does it fit?
The RV Fuel Vault is engineered for the commercial Ford (and Ram) chassis that Dynamax motorhomes are built on. Here is how the lineup breaks down:
| Chassis | Dynamax models |
|---|---|
| Super C (Ford F-550 / F-600 diesel) | Isata 6, Force HD, DX3 |
| Super C (Ram 5500 diesel) | Isata 5 |
Not sure which one you have? The fitment finder confirms your exact year, make, model, and floorplan in seconds.
Why Dynamax owners need it
Dynamax coaches sit on heavy-duty diesel chassis with large fuel tanks and exposed diesel and DEF caps. That combination is exactly what fuel thieves look for. The RV Fuel Vault is engineered for both the Ford and Ram 5500 commercial filler necks, where standard automotive locking caps simply do not fit.
- Stops fuel theft & siphoning — a keyed, virtually unbreakable door over the cap.
- Prevents contamination — no more open access to add water, sugar, or the wrong fluid.
- Built tough — 3/16″ fiber-filled polymer that is non-corrosive and resists prying.
- Factory-finished look — covers the ugly exposed cap for a clean, finished appearance.
Installation & pricing
The RV Fuel Vault is a bolt-on upgrade that most owners install in 8–15 minutes with basic hand tools — no drilling, no cutting, and no permanent modifications. Pricing starts at $109.95 (Founders Edition) for a single door, $219.90 for a set of two, and $329.85 for the 3-Pack that includes a DEF cover. Every order ships free in the Continental U.S. and is backed by a Limited Lifetime Warranty and a 30-day satisfaction guarantee.
Frequently asked questions
Does the RV Fuel Vault fit a Dynamax Isata 6?
Yes. The Isata 6 is built on the Ford F-600 Super C chassis, which the RV Fuel Vault is purpose-built to fit. The 3-Pack also covers the DEF cap.
Does it fit a Dynamax Isata 5 on the Ram 5500?
Yes. The RV Fuel Vault has a version engineered for the Ram 5500 filler-neck geometry used on the Isata 5, covering both the diesel and DEF caps.
What does it cost and how long is the install?
Pricing starts at $109.95 (Founders Edition) per door, with the DEF 3-Pack at $329.85 and free U.S. shipping. Most owners install it in 8 to 15 minutes with basic hand tools.
Lock down your Dynamax fuel cap
Confirm your motorhome fits and protect your fuel cap with the only purpose-built locking fuel door for RVs.
Check fitment & order →
See the Dynamax fitment page
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