Big Side-Mount Tank. Big Target
M2 106 • M2 112 • MT45 / MT55 • S2G • XC Custom Chassis
Freightliner M2 and Custom Chassis platforms use large side-mount tanks. The Large Fuel Vault door covers the filler and the cap together — locked, armored and bolted on.
Founders Edition pricing — starting at $159.95 (Save up to $110 on the 3-Pack) · Security screws included
Freightliner Builds the Truck — Not the Fuel Lock
Freightliner commercial trucks leave the factory as incomplete chassis. The body builder finishes the truck, and nobody adds a lock to the fuel filler.
- Large side-mount tanks hold a lot of diesel — and the cap is exposed
- M2 box, flatbed and dump trucks park loaded overnight
- Step vans sit at depots between delivery routes
- Locking gas caps are defeated with basic hand tools
- Contaminated fuel can put a medium-duty truck out of service
- Fuel loss across a fleet adds up fast
The Locking Fuel Door for Your Freightliner 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.
- Large armored locking door covers the filler and cap together
- One Large door per truck across the M2, MT45, MT55, S2G and XC
- Bolt-on install in 8–15 minutes
- Tamper-resistant security screws included
- High-strength UV-stable composite
- 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.
Freightliner Owners Who Need This
Delivery Fleets
M2 box trucks and MT step vans park at depots overnight.
Construction
M2 dump and flatbed trucks sit at jobsites with full tanks.
Municipal Fleets
Public-works M2s park in open yards — lock the diesel.
Freightliner Dealers
Add the Large door at upfit or delivery.
Utility Fleets
Bucket and line trucks on M2 chassis work remote sites.
Shuttle & Specialty
XC custom chassis shuttles park in open lots.
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 Freightliner trucks does it fit?
Our fitment guide lists the M2 106 (our most common Freightliner fit), M2 112, MT45 and MT55 step vans, S2G gas chassis, and XC Series custom chassis — each takes one Large door.
Which door size do I need?
The Large door (WTFV-1002L, $169.95). It covers the filler and the cap together on Freightliner side-mount tanks.
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 on Your Freightliner — 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
Freightliner Fitment Guide
Door size and how many doors we recommend for each model.
| Model | Years | Door Size | Doors | Notes |
|---|---|---|---|---|
| M2 106 | 2010–2026 | Large | 1 | Large door. Most common Freightliner fit. |
| M2 112 | 2010–2026 | Large | 1 | Large door. |
| MT45 Step Van | 2012–2026 | Large | 1 | Walk-in delivery chassis. |
| MT55 Step Van | 2012–2026 | Large | 1 | Walk-in delivery chassis. |
| S2G Gas Chassis | 2018–2026 | Large | 1 | Gasoline medium duty. |
| XC Series Custom Chassis | 2012–2026 | Large | 1 | Shuttle and specialty builds. |