Sierra HD Muscle. Zero Fuel Security
Sierra 3500HD–6500HD • Savana Cutaway
GMC Sierra HD chassis cabs and Savana cutaways share GM filler hardware — the same exposed cap, the same fix. The Work Truck Fuel Vault bolts on and locks the diesel, plus the DEF on 4500HD and up.
Founders Edition pricing — starting at $159.95 (Save up to $110 on the 3-Pack) · Security screws included
GMC Builds the Truck — Not the Fuel Lock
GMC commercial trucks leave the factory as incomplete chassis. The body builder finishes the truck, and nobody adds a lock to the fuel filler.
- Sierra HD chassis cabs ship without a locking fuel door
- Sierra 4500HD, 5500HD and 6500HD leave diesel and DEF exposed
- Savana cutaway box and service builds have an open cap
- Locking gas caps are a token gesture against a pry bar
- DEF contamination can derate the truck and cost a crew day
- Trucks park overnight in open yards and jobsites
The Locking Fuel Door for Your GMC Truck
The Work Truck Fuel Vault is an armored, locking fuel door that bolts on at the filler. It covers the whole fill area, not just the cap.
- Armored locking door over the diesel filler
- Second door locks the DEF filler on 4500HD, 5500HD and 6500HD
- Small door for 3500HD–5500HD; Large door for 6500HD
- Bolt-on install in 8–15 minutes
- Tamper-resistant security screws included with every door
- Limited Lifetime Warranty and 30-day money-back guarantee
The Part The Factory Forgot
The Work Truck Fuel Vault is an armored, locking fuel door that covers the entire fuel access area on your work truck. No more exposed caps. No more easy targets.
Why Didn't This Exist Before?
Despite billions lost to fuel theft every year, nobody built a real solution for commercial work trucks. Here's why.
"Good Enough" Thinking
The industry defaulted to cheap aftermarket locking gas caps. A $15 key-locked cap was considered good enough — until thieves proved otherwise with a pair of pliers.
Upfitters Focus on the Body, Not the Cap
Manufacturers like Knapheide and Reading engineer every compartment lock on the service body — but the chassis fuel pocket belongs to Ford or Ram. Nobody owned the gap.
The Zero-Drill Engineering Problem
Consumer billet doors are made for flat pickup beds. The recessed fuel pocket on a commercial chassis is a completely different geometry — and drilling risks voiding the chassis warranty.
The Cost Was Just "Absorbed"
Fleets treated fuel theft like weather damage. A $500 siphoning hit got buried in operating expenses. Without a purpose-built product available, the problem was simply accepted.
The Work Truck Fuel Vault is the industry's first drop-in armored fuel door that uses existing factory mounting points. No drilling. No cutting. No warranty risk.
GMC Owners Who Need This
Contractors
Sierra HD service and dump bodies — lock the fuel like the tools.
Utility Fleets
Remote-parked trucks need the diesel and DEF locked.
GMC Fleet Dealers
A simple accessory add-on for HD chassis cab deliveries.
Box & Service Vans
Savana cutaways sit loaded overnight with an open cap.
Municipal Fleets
Cut fuel shrink across public-works GMC trucks.
Landscape Fleets
Trucks parked at job sites and lots overnight stay protected.
Chassis Compatibility
Purpose-built for the most popular commercial chassis platforms in the industry.
Ford
Super Duty & Commercial Chassis
- F-350 Chassis Cab
- F-450 Chassis Cab
- F-550 Chassis Cab
- F-600 Chassis Cab
- E-350 / E-450
- F53 Workhorse
Ram
Chassis Cab Heavy Duty
- Ram 3500 Chassis Cab
- Ram 4500 Chassis Cab
- Ram 5500 Chassis Cab
Locking Fuel Cap vs. Fuel Vault
See how The Work Truck Fuel Vault compares to the alternatives.
| Feature | Locking Fuel Cap | The Work Truck Fuel Vault |
|---|---|---|
| Protection Type | Cap only | Full armored door over the fuel fill area |
| Tamper Resistance | Low — pliers remove in seconds | High — armored composite, security screws |
| Prevents Siphoning | Partial — hose can bypass | Yes — locked door blocks access |
| DEF Protection | Not included | Second door locks the DEF filler |
| Install Time | 1 minute screw-on | 8–15 min bolt-on (one time) |
| Warranty | None or 90 days | Limited Lifetime Warranty |
Feature comparison between standard locking fuel cap and The Work Truck Fuel Vault
Protection Type
Cap only
Full armored door over the fuel fill area
Tamper Resistance
Low — pliers remove in seconds
High — armored composite, security screws
Prevents Siphoning
Partial — hose can bypass
Yes — locked door blocks access
DEF Protection
Not included
Second door locks the DEF filler
Install Time
1 minute screw-on
8–15 min bolt-on (one time)
Warranty
None or 90 days
Limited Lifetime Warranty
Our Guarantee
Limited Lifetime Warranty
Built to last. Warranted against defects in material and workmanship for the life of the vehicle on which it was originally installed.
30-Day Money Back
Not satisfied? Return within 30 days of receipt for a full refund. No questions asked.
Free Replacements
If your Fuel Vault is defective under normal use within the warranty period, we replace it at no charge.
Frequently Asked Questions
Which GMC trucks does it fit?
Our fitment guide lists the Sierra 3500HD Chassis Cab (one Small door), Sierra 4500HD and 5500HD (Small door, two recommended for diesel plus DEF), Sierra 6500HD (Large door, two recommended), Savana Cutaway 3500 (one Small door), and Savana Cutaway 4500 (confirm bezel size before ordering).
Is the GMC fit the same as Chevrolet?
Sierra HD and Savana share GM filler hardware with the Silverado HD and Express, so the door sizes line up model for model.
Why two doors on the Sierra 4500HD and up?
Those trucks have exposed diesel and DEF fillers. One door locks each.
How long does install take?
About 8 to 15 minutes per door with basic hand tools. It bolts on — no welding and no changes to the body or chassis.
How much does it cost?
The Small door (WTFV-1001S) is $159.95 and the Large door (WTFV-1002L) is $169.95. A 2-pack of Small doors (WTFV-2001S) is $309.95. Tamper-resistant security screws are included with every door at no extra cost. UPS shipping is calculated at checkout. Fleet and dealer volume pricing is available.
Is there a warranty?
Yes — a Limited Lifetime Warranty and a 30-day money-back guarantee.
Lock the Diesel and DEF on Your Sierra HD — Starting at $159.95
Armored locking fuel door. Security screws included. Bolts on in about 15 minutes. UPS shipping calculated at checkout.
Secure checkout • Live UPS shipping • No charge until your order ships
GMC Fitment Guide
Door size and how many doors we recommend for each model.
| Model | Years | Door Size | Doors | Notes |
|---|---|---|---|---|
| Sierra 3500HD Chassis Cab | 2015–2026 | Small | 1 | Small door. |
| Sierra 4500HD | 2019–2026 | Small | 2 | Diesel plus DEF. |
| Sierra 5500HD | 2019–2026 | Small | 2 | Two doors recommended. |
| Sierra 6500HD | 2019–2026 | Large | 2 | Large door. |
| Savana Cutaway 3500 | 2010–2026 | Small | 1 | Box and service body builds. |
| Savana Cutaway 4500 | 2010–2026 | Small or Large — confirm bezel | 1 | Confirm bezel size. |
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