The UWS ST-100-COMBO-W moves diesel and other non-flammable liquids out to the equipment that cannot come to the pump. One hundred gallons is the top of the UWS range and the point at which a transfer tank stops being a convenience and becomes the reason the truck exists. It is around 710 lb of diesel, so payload, not bed space, is usually the binding constraint. The combo layout stacks the storage on top of the tank rather than beside it, so the tool box costs you no additional bed floor at all. Fuel underneath, tools above, one footprint. The tank is welded from 14-gauge high-strength steel and 100% pressure-tested before it ships, with internal baffles inside so the load does not surge forward every time you brake. The white powder coat is the fleet finish. It matches a white work truck, and on a hot job site a white tank sits noticeably cooler in direct sun than a black one. The built-in tool box adds 11.4ft³ of lockable, weather-sealed storage on top of the tank, using the same patented RigidCore foam-filled lid, MicroSeal gasket and stainless steel lock handles as a standalone UWS chest, so you are not giving up bed space to carry tools as well as fuel. The fill cap is a lockable commercial-grade vented unit with a reinforced collar, and the drain plug sits nearly flush with the tank floor so it actually empties. At 60" long and 31" wide it is a spec-fit product, not a vehicle-specific one, so measure your bed floor and the gap between the wheel wells before you order. UWS rates this tank as DOT-compliant for transporting Class 3 combustible fuels only, such as diesel.
What's Included:
1 x UWS 100-gallon transfer tank
2 x keys for the tool box lock handles (UWS supplies keys with combo models only)
1 x filler neck and cap
1 x drain plug, 3/8"
NOT included, and you have to buy them separately: mounting hardware (UWS states you must purchase your own), an automatic shutoff nozzle, a fuel filter, a padlock for the fill cap, and any pump, hose or transfer kit
Features
100 Gallons of Usable Capacity This tank holds 100 gallons, which is about 710 lb of diesel once it is full. That is the number to plan around, not the empty weight: a full ST-100-COMBO-W puts roughly 957 lb into the bed before you load anything else, so check it against your truck's payload rating.
14-Gauge High-Strength Steel, Welded as One Piece The tank is formed from 14-gauge high-strength steel and welded into a single piece, which removes the seams that are the usual place a tank starts to weep. Every tank is 100% pressure-tested before it ships.
White Finish The white powder coat is the standard fleet finish and the one that stays coolest in direct sun. UWS backs the finish for one year and the tank itself for life.
Internal Baffles Baffles are partial walls welded inside the tank. They stop 710 lb of liquid from surging forward under braking or sideways through a corner, which is a handling and a safety issue on a loaded truck, and they add structural stiffness to the tank at the same time.
Lockable Commercial-Grade Vented Fill Cap The fill cap vents properly as the tank drains, which is what stops a tank pulling a vacuum and slowing the flow, and it has a reinforced collar and a lockable hasp so the contents are not an open invitation overnight. Bring your own padlock; UWS does not supply one.
Drain Plug Set Nearly Flush The drain plug sits nearly flush with the bottom of the tank so it actually empties, which matters if you ever switch what you are hauling or need to drop the weight before moving the tank. UWS specifies removing all liquid before relocating a tank.
1/8" Mounting Tabs and Welded Lift Hooks The mounting tabs are 1/8" steel, so bolting the tank down does not deform the tab over time, and there are lift hooks welded to the back for getting the tank in and out of the bed with a hoist. Mounting hardware itself is not included.
Built-In Tool Box with 11.4ft³ of Storage The tool box is integrated into the tank rather than sitting next to it, so you get 11.4ft³ of lockable storage without giving up any more bed floor. It is built from .080" aluminum even on this steel tank, which is why the steel-aluminum combo weighs less than a full-steel equivalent.
Patented RigidCore Lid and MicroSeal Gasket The lid is two metal plates with solid foam between them, which is what keeps it from flexing, binding or warping when someone inevitably stands on it. The MicroSeal gasket seals out water and dust, and the lid self-opens to 90 degrees and self-closes, so it is a one-handed job.
Stainless Steel Lock Handles, Both Sides Stainless steel paddle handles are linked by a connecting rod so the box opens from either side of the truck, and the rod runs inside an enclosure that protects it from being bent or pried, which is the usual way a tool box lock gets defeated.
Fitment & Compatibility
Truck or Application
Fit
Full-size long-bed trucks (8' bed)
✓ Yes
Full-size short-bed trucks (5'8" to 6'6" bed)
✓ Yes if your bed floor is at least 60" long, measure first
Compact and mid-size trucks (Tacoma, Ranger, Colorado, Frontier)
✗ No, 60" x 31" is too large and the loaded weight is too high
Short beds with a gooseneck hitch fitted
● Measure carefully, a tank this size usually conflicts with the ball
Flatbeds, trailers and stationary use
✓ Yes, on a flat surface rated for the loaded weight
Fit guidance: This is a spec-fit product, not a vehicle-specific kit, so it fits whatever bed it physically fits. The tank is 60" long, 31" wide and 24" tall, and UWS notes the fill cap adds about 2-3/4" to the overall height, which is the figure that decides whether the tank clears a tonneau or sits below the bed rails. Measure your bed floor length and the gap between the wheel wells before ordering. Filled with diesel this tank carries about 710 lb of fuel on top of its 247 lb empty weight, roughly 957 lb in total, so confirm your truck's payload rating. Mounting hardware is not included.
Specifications
UWS Part Number: ST-100-COMBO-W
Tank Capacity: 100 gallons
Tank Style: Combo
Material: 14-gauge high-strength steel
Wall Thickness: 14 gauge
Finish: White Powder Coat
Overall Length: 60"
Overall Width: 31"
Overall Height: 24"
Upper Section Height: 15"
Lower Tub Width: 22"
Tub Width: 9"
Tub Height: 9"
Tool Box Storage Volume: 11.4ft³
Tool Box Material: .080" aluminum
Tool Box Lid: Single Lid, patented RigidCore foam-filled
Tool Box Latch: Paddle Handle, stainless steel, connecting rod both sides
Tool Box Weather Seal: MicroSeal gasket
Internal Baffles: Yes
Fill Cap: Lockable commercial-grade vented cap with reinforced collar (padlock not included)
Drain Plug: 3/8", set nearly flush with the tank floor
Pressure Test: 100% pressure-tested
Mounting: 1/8" steel tabs with welded lift hooks (mounting hardware not included)
DOT Rating: DOT-compliant for transporting Class 3 combustible fuels only, such as diesel
Keys Supplied: 2, for the tool box lock handles
Intended Use: Private use only; UWS states the tank is not intended for commercial use and does not meet 49 CFR 393.65 or 393.67
Not Compatible With: Gasoline and other flammable fuels, diesel exhaust fluid (DEF), and other corrosive materials
Type: Set the tank into the bed and bolt it down through the factory mounting tabs · Time: About 1 hour with a second person or a hoist · Tools: Drill and a 3/8" drill bit, ratchet and socket set, tape measure and a marker, plus a hoist or a second person to lift the tank · Difficulty: Easy, and UWS rates the installation difficulty as Easy
Empty the tank completely before you ever move it; UWS states it should be lifted only when empty. Before you drill into the bed, look underneath and confirm the bit cannot reach a brake or fuel line, wiring or the fuel tank, and keep fasteners far enough from the fuel tank that a collision cannot drive one into it. The tank must finish up securely bolted to the bed. Mounting hardware is not supplied, so match the fastener size to your bed and use backing plates or large washers underneath; UWS's general torque guidance is 16 ft-lb for a 3/8" bolt and 28 ft-lb for a 1/2" bolt, but if your hardware comes with its own figures, use those. The tank must stay vented at all times, must not be pressurized, and UWS requires an automatic shutoff nozzle and a fuel filter, none of which are supplied. Read the UWS installation manual through before you start, and check your state and local rules on transporting fuel before the first fill.
Resources
Everything you need for your UWS 100-Gallon Combo Steel Transfer Tank with 11.4ft³ Tool Box, White, in one place.
Warranty. Limited lifetime warranty from UWS on the tank, with one year on the finish and one year on parts. Damage from overloading, improper installation, or hauling a liquid outside the tank's rating is not covered.
Free shipping. This item ships free to the lower 48 states. Because it is an oversized item, it ships by freight and typically arrives in 3 to 7 business days.
Inspect on delivery. Please inspect the packaging before signing. If you see any damage, note it on the delivery receipt and contact us right away, and we will make it right.
Compliance. DOT-compliant for transporting Class 3 combustible fuels only, such as diesel. UWS states this tank is NOT approved for transporting flammable fuels such as gasoline, must never be connected to a vehicle's fuel system or used as an auxiliary fuel tank, and is not compatible with diesel exhaust fluid (DEF) or other corrosive materials. UWS also states the tank is for private use only, is not intended to be used commercially, and does not meet 49 CFR 393.65 and 393.67.
About UWS
UWS, United Welding Services, builds truck tool boxes and liquid transfer tanks and is part of the CURT Group family of towing and truck accessory brands under Lippert. The company is best known for two things it engineered rather than bought in: the patented RigidCore lid, which sandwiches solid foam between two metal plates so a tool box lid does not flex, bind or warp under load, and the MicroSeal gasket that keeps water, dust and road grime out of the box. Those details show up across the whole catalog, from a crossover box to a 100-gallon combo tank.
UWS steel transfer tanks are the heavier-duty half of the range. Each one is welded from 14-gauge high-strength steel as a single piece to remove seams as a leak path, fitted with internal baffles so the load does not surge when you brake or corner, given a lockable commercial-grade vented fill cap and a near-flush drain plug, and 100% pressure-tested before it ships. Mounting tabs are 1/8" steel and there are welded lift hooks on the back for getting the tank in and out of the bed.
Prestige Truck is an authorized UWS dealer. Everything we ship is new, covered by the full UWS factory warranty, and backed by UWS's own service and parts support.
UWS Transfer Tanks | Features & Benefits
UWS's own walkthrough of the transfer tank line. It covers what is inside every tank: the internal baffles that stop the load sloshing when you brake, the lockable commercial-grade vented fill cap, the flush drain plug, and the 100% pressure test each tank goes through before it leaves the plant.
Worth four minutes before you buy, because it explains why two tanks of the same capacity are not the same tank.
Tool Box Vs. Mud Vs. Pressure Washer | MicroSeal Weather Test
UWS buries a tool box in mud and then takes a pressure washer to it, to show what the MicroSeal gasket on this combo's lid is actually doing.
Worth watching if the box is going to live in an open bed through a winter of road salt and spray.
UWS | True Fit Toolboxes
UWS's film on how its tool boxes are built to fit. It covers the RigidCore foam-filled lid, the MicroSeal gasket that keeps weather out, and the stainless steel lock handles with the connecting rod.
The tool box on this combo uses the same construction, so this is the clearest look at the storage half of the product.
Frequently Asked Questions
Straight answers on specs, fit and support
What can I legally haul in this tank, and what can I not?
Diesel is the intended use. UWS rates the tank DOT-compliant for transporting Class 3 combustible fuels only, such as diesel, and for non-flammable liquids including water. The exclusions are explicit in UWS's own installation manual and worth reading before you buy: it is NOT approved for flammable fuels such as gasoline; it must never be connected to your truck's fuel system or used as an auxiliary tank; and it is not compatible with diesel exhaust fluid or other corrosive materials, so DEF is out. UWS also states the tank is for private use only, is not intended for commercial use, and does not meet 49 CFR 393.65 or 393.67, which are the federal fuel-system rules for commercial motor vehicles. If you run under a DOT number, check that against your own compliance requirements before ordering.
Will it fit my truck bed?
Measure before you order. The tank is 60" long, 31" wide and 24" tall, and the fill cap adds about 2-3/4" on top of that. The two numbers that decide it are your bed floor length and the gap between your wheel wells. A tank this size is a full-size truck product; it will not work in a compact or mid-size bed.
How much does it weigh when it is full?
The tank is 247 lb empty. Diesel runs about 7.1 lb per gallon, so a full 100 gallons adds roughly 710 lb, for about 957 lb sitting in the bed before any other cargo. That is more than a half-ton truck's remaining payload in many configurations, so check the door-jamb sticker rather than assuming. Always drain the tank completely before relocating it.
What exactly comes in the crate?
UWS's installation manual lists the carton contents as the tank, two keys, the filler neck and cap, and a 3/8" drain plug. The keys are for the tool box lock handles and UWS supplies them with combo models only, which includes this one. Mounting hardware is not included and UWS is explicit that you must buy your own to suit your bed. You will also need an automatic shutoff nozzle, which UWS requires and does not provide, and a fuel filter. There is no pump, hose or padlock in the crate.
How much will the tool box actually hold?
The tool box gives you 11.4ft³ of storage, and because it is built into the tank it does not cost you any additional bed floor. It uses the patented RigidCore foam-filled lid, a MicroSeal gasket to keep weather out, and stainless steel paddle handles linked by a connecting rod so you can open it from either side of the truck.
How does it ship, and what is the warranty?
This is a freight item, not a parcel item. At about 252 lb it moves by LTL freight, so expect a delivery appointment and plan how you will get it off the truck: a forklift, a loading dock or several people. The steel tanks have welded lift hooks on the back that make the final placement much easier. UWS covers the tank with a limited lifetime warranty, with one year on the finish and one year on parts.
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