Duramax Diesel. DEF. Both Wide Open
Silverado 3500HD–6500HD • Express Cutaway • Low Cab Forward
Silverado HD chassis cabs, Express cutaways and Low Cab Forward trucks all run exposed fuel caps under commercial bodies. On the 4500HD, 5500HD and 6500HD the DEF filler sits right beside the diesel. The Work Truck Fuel Vault locks both.
Founders Edition pricing — starting at $159.95 (Save up to $110 on the 3-Pack) · Security screws included
Chevrolet Builds the Truck — Not the Fuel Lock
Chevrolet commercial trucks leave the factory as incomplete chassis. The body builder finishes the truck, and nobody adds a lock to the fuel filler.
- Silverado HD chassis cabs ship with no locking fuel door
- 4500HD, 5500HD and 6500HD have diesel and DEF fillers exposed side by side
- Express cutaway box and shuttle builds leave the cap open to anyone
- Locking gas caps can be pried off in seconds
- DEF contamination can derate a truck and force an expensive repair
- Trucks park overnight at jobsites and yards with little security
The Locking Fuel Door for Your Chevrolet 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 and LCF 6500XD
- Bolt-on install in 8–15 minutes with hand tools
- 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.
Chevrolet Owners Who Need This
Contractors
Silverado HD service and dump trucks carry diesel worth stealing.
Utility Fleets
Lock diesel and DEF on trucks that park at remote sites.
Chevy Commercial Dealers
An easy add-on for every HD chassis cab delivery.
Delivery & Box Trucks
Express cutaway and LCF box trucks sit loaded overnight.
Municipal Fleets
Stop fuel shrink across city and county Chevy trucks.
Shuttle Operators
Express cutaway shuttles park in open lots between runs.
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 Chevrolet trucks does it fit?
Our fitment guide lists the Silverado 3500HD Chassis Cab (one Small door), Silverado 4500HD and 5500HD (Small door, two recommended for diesel plus DEF), Silverado 6500HD (Large door, two recommended), Express Cutaway 3500 (one Small door), Express Cutaway 4500 (check bezel size before ordering), Low Cab Forward 4500 and 5500 (one Small door), and Low Cab Forward 6500XD (one Large door).
Why two doors on the 4500HD, 5500HD and 6500HD?
Those trucks have the diesel and DEF fillers exposed. One door locks the diesel and a second locks the DEF.
Which size do I need for an Express Cutaway 4500?
Check the bezel size before ordering — the Express 4500 can take the Small or Large door depending on the build. Find My Fit or our team can help confirm.
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 Silverado 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
Chevrolet Fitment Guide
Door size and how many doors we recommend for each model.
| Model | Years | Door Size | Doors | Notes |
|---|---|---|---|---|
| Silverado 3500HD Chassis Cab | 2015–2026 | Small | 1 | Small door standard fit. |
| Silverado 4500HD | 2019–2026 | Small | 2 | Diesel plus DEF exposed. |
| Silverado 5500HD | 2019–2026 | Small | 2 | Two doors recommended. |
| Silverado 6500HD | 2019–2026 | Large | 2 | Large door for the main fill. |
| Express Cutaway 3500 | 2010–2026 | Small | 1 | Box, service, and shuttle builds. |
| Express Cutaway 4500 | 2010–2026 | Small or Large — confirm bezel | 1 | Check bezel size before ordering. |
| Low Cab Forward 4500 | 2016–2026 | Small | 1 | Isuzu-built cab-over platform. |
| Low Cab Forward 5500 | 2016–2026 | Small | 1 | Side-mounted tank, exposed cap. |
| Low Cab Forward 6500XD | 2019–2026 | Large | 1 | Large door. |
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