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The RV Fuel Vault™
Built for the Force HD

Dynamax Force HD Locking Fuel Door — Security Your Super C Deserves

The Dynamax Force HD is one of the most capable Super C motorhomes on the road — built on the Ford F-550 with the 6.7L Power Stroke. But Dynamax left the diesel and DEF caps completely exposed. The RV Fuel Vault is the exact-fit armored locking enclosure that finally seals them.

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The RV Fuel Vault — Dynamax Force HD — locking fuel door for motorhomes

Why a Locking Gas Cap Is Not Enough

  • ✖Your Dynamax Force HD left the factory with completely exposed diesel and DEF caps — no fuel door
  • ✖The F-550 Power Stroke carries 50-80 gallons of diesel — a theft magnet at campgrounds and truck stops
  • ✖DEF contamination from tampering can destroy your emissions system — a $5,000-$10,000 repair
  • ✖Cheap locking caps can be pried off in seconds and leave your DEF tank completely unprotected
  • ✖Road debris and diesel splash-back damage the paint around your exposed filler area

Why a Locking Fuel Door Beats a Locking Gas Cap

  • Factory-finished look — eliminates exposed diesel and DEF caps on your Force HD
  • Precision-engineered for the Dynamax Force HD on Ford F-550 filler neck configuration
  • Tamper-resistant keyed lock secures both diesel fuel and DEF fluid simultaneously
  • High Impact Reinforced Material — built for full-time Super C ownership
  • Bolt-on in 8-15 minutes — no drilling, no cutting, no modifications
  • Corrosion-proof construction rated for year-round use in any climate

Before & After: Your RV's Exposed Fuel Cap vs. a Locking Fuel Door

Exposed caps on Force HD — no security — exposed RV fuel cap before locking fuel door
✖ Exposed caps on Force HD — no security
RV Fuel Vault installed — sealed and locked — RV Fuel Vault locking fuel door installed
✓ RV Fuel Vault installed — sealed and locked

Why You Need a Locking Fuel Door

Lead with finish. End with security.

Factory-Finished Look

Eliminates the exposed plastic caps on your Force HD. Your rig finally looks factory-complete.

Fuel Theft Prevention

Keyed lock stops siphoning at campgrounds, rest stops, and storage facilities.

DEF Contamination Defense

Prevents tampering with your DEF tank — avoids $5K-$10K SCR system repairs.

Vandalism Protection

Tamper-resistant design deters opportunistic damage to your fuel system.

How It Installs — 8–15 Minutes, No Drilling, No Cutting

8–15 Minutes

Average install time

Basic Hand Tools

No special equipment needed

100% Reversible

No drilling, no cutting, no mods

Compatible Ford F-550 (Dynamax Force HD) Motorhomes

The Dynamax Force HD is built on the Ford F-550 with the 6.7L Power Stroke diesel. Like all F-550 Super C motorhomes, both diesel and DEF filler necks are completely exposed from the factory.

ManufacturerModels / Floorplans
Dynamax Force HDAll floorplans (34KD, 36FK, 37BH, etc.) on Ford F-550
Dynamax DX3All floorplans on Ford F-550
Also fits other F-550 Super CEntegra Accolade XT, Jayco Seneca
Don't see your model? Use the Fitment Finder — we likely fit your rig.

Frequently Asked Questions

Common questions about The RV Fuel Vault on Ford F-550 (Dynamax Force HD) motorhomes

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Single Door, Set of 2, or 3-Pack · Limited Lifetime Warranty · 30-Day Guarantee

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Proudly Made in the USA · Patent Pending · In Stock — Ships in 3 Business Days