Best Auxiliary Tanks For Diesels: Compare 10 Truck Tanks

#1 · Best Overall

1. RDS 70326 Rectangular Tank

• Capacity: 69 gallons
• Material: Aluminum
• Compatible with Vehicle Type: Multiple vehicle types
• Weight: 16 oz

Best for: Long-haul diesel capacity.

Why it ranks #1: The 69-gallon aluminum tank is listed at 57 x 18 x 16 inches, and its description says diesel can gravity-feed to the vehicle tank.

A 69-gallon aluminum tank gives this RDS unit its clearest advantage: substantial onboard reserve for truck owners who want auxiliary diesel connected to the vehicle’s fuel supply. Its rectangular 57-by-18-by-16-inch dimensions also give buyers concrete measurements to check against available bed space before planning an installation.

RDS says diesel can gravity-feed from the bottom of the tank to the vehicle fuel tank, making the auxiliary supply useful for extending onboard fuel availability. The aluminum construction avoids a steel tank’s material choice, while the stated 57-by-18-by-16-inch footprint helps assess truck-bed fit. An optional Diesel Install Kit is mentioned, but the listing does not specify what it includes, so installation planning should account for that uncertainty.

Skip it if you need an included installation kit; the listing only mentions an optional Diesel Install Kit, while Dee Zee DZ92556NSB lists installation hardware.

This suits truck owners prioritizing a large auxiliary diesel reserve and a gravity-feed connection. Its 57-inch length and 18-inch width are meaningful fit considerations, and buyers should plan separately for the optional installation kit.

Listed on Amazon as: RDS MFG INC Rectangular Auxiliary Fuel Tank – 69 Gallon

#2 · Best 45-Gallon Option

2. RDS 71083 Rectangular Tank

• Capacity: 45 gallons
• Material: Aluminum
• Weight: 42 lb

Best for: Welded-seam aluminum choice.

Why it ranks #2: This 45-gallon aluminum RDS tank has fully welded seams and is described as supporting auxiliary fueling, including diesel gravity feed.

Fully welded seams are a key differentiator on this 45-gallon RDS aluminum tank, giving buyers a specific construction feature to consider for fuel transport. RDS also states that diesel can gravity-feed from the tank bottom to the vehicle tank, linking its transfer-tank role to auxiliary vehicle fueling.

The 45-gallon capacity provides a substantial reserve, and the aluminum body is described as not rusting, an appealing material characteristic for owners comparing tank construction. Fully welded seams are specified for durability. RDS says diesel can gravity-feed from the bottom to the vehicle fuel tank, which supports an auxiliary supply workflow. The supplied details do not give dimensions, so buyers cannot assess its exact bed footprint from this listing alone.

Skip it if you need published dimensions before planning placement; RDS MFG INC 70326 lists a 57-by-18-by-16-inch footprint.

This suits buyers seeking a 45-gallon aluminum tank with welded seams and a stated diesel gravity-feed connection. The missing dimensions are a practical planning limit, so it is less straightforward when bed space is tightly constrained.

Listed on Amazon as: RDS MFG INC 71083 Rectangular Auxiliary/Transfer Fuel Tank – 45 Gallon Capacity

#3 · Best Wedge Design

3. RDS 71783 Wedge Tank

• Capacity: 63 gallons
• Material: Aluminum
• Compatible with Vehicle Type: Car, Truck, Van
• Weight: 61 lb

Best for: Wedge-shaped large reserve.

Why it ranks #3: The 63-gallon aluminum wedge tank is described as providing auxiliary fueling and diesel gravity feed, with listed dimensions of 52 x 19 x 18 inches.

The wedge form and 63-gallon capacity define this RDS auxiliary tank, pairing a substantial fuel reserve with a shape distinct from the rectangular models. Its aluminum construction and 52-by-19-by-18-inch measurements give car, truck, and van owners useful material and placement details to assess.

RDS states that diesel can gravity-feed from the tank bottom to the vehicle fuel tank, making this more than a standalone storage container for compatible setups. The 63-gallon capacity supports a sizable auxiliary reserve, while the 52-by-19-by-18-inch dimensions help buyers plan placement across the listed car, truck, and van vehicle types. Aluminum is the specified material. The supplied details do not explain the wedge geometry’s fit advantage or provide installation-kit contents.

Skip it if you need a toolbox combined with the fuel tank; RDS MFG INC 72548 pairs a 60-gallon tank with toolbox storage.

This suits owners of listed cars, trucks, or vans seeking a large aluminum auxiliary reserve with a stated gravity-feed connection. The wedge’s practical fit implications are not detailed, so placement should be assessed carefully.

Listed on Amazon as: RDS MFG INC 71783 Auxiliary Fuel Tank 63Gal Wedge

#4

4. RDS 71804 Auxiliary Tank

• Capacity: 37 gallons
• Material: Aluminum
• Compatible with Vehicle Type: Car
• Weight: 77 lb

Best for: Low-profile aluminum reserve.

Why it ranks #4: This 37-gallon aluminum RDS tank is described as connecting to the vehicle tank for diesel gravity feed and has a relatively low 9-inch listed height.

At 9 inches high, this 37-gallon RDS aluminum tank offers a notably shallow listed profile for buyers managing vertical space. RDS also describes diesel gravity-feeding from the tank bottom to the vehicle tank, giving the low-profile form a practical role as an auxiliary fuel reserve rather than storage alone.

The 50-by-20-by-9-inch dimensions let truck owners assess a low-height placement, while 37 gallons adds auxiliary capacity without relying on the larger tank sizes in this roundup. RDS states that diesel can gravity-feed from the tank bottom to the vehicle fuel tank, supporting an integrated fuel workflow. Aluminum is the specified material. The listing also allows gasoline fueling only when siphoned from the top with an electric fuel pump, a distinction relevant to fuel-use planning.

Skip it if you need more than 37 gallons; RDS MFG INC 70326 provides a 69-gallon capacity and also describes diesel gravity feed.

This RDS tank suits buyers prioritizing a shallow 9-inch profile and a stated diesel gravity-feed connection. Its 37-gallon capacity is the boundary to weigh, along with the 50-by-20-inch footprint when planning placement.

Listed on Amazon as: RDS MFG INC Auxiliary Fuel Tank 37Gal – 71804

#5 · Best Toolbox Combo

5. RDS 72548 Toolbox Combo

• Capacity: 60 gallons
• Material: Alloy Steel, Aluminum, Stainless Steel
• Compatible with Vehicle Type: Truck
• Weight: 16 oz

Best for: Fuel-and-toolbox truck setup.

Why it ranks #5: The 60-gallon RDS combo adds a toolbox, and its description says diesel can gravity-feed from the tank bottom to the vehicle tank.

A 60-gallon tank paired with toolbox storage makes this RDS combination useful to truck owners consolidating fuel and equipment in one unit. Its 55-by-20-by-19.5-inch dimensions provide a practical starting point for checking bed fit, while the listing identifies it as a truck-compatible accessory.

The combination format puts a storage compartment and a 60-gallon fuel tank together, supporting a single truck-bed setup for tools and auxiliary fuel. RDS describes its tanks as connecting to the vehicle fuel tank, with diesel able to gravity-feed from the bottom. That connection can extend the truck’s available fuel supply; the listed dimensions help assess placement, though the provided details do not describe toolbox organization or installation hardware.

Skip it if you want a simpler aluminum tank without toolbox storage; RDS MFG INC 71083 is a 45-gallon rectangular alternative.

Truck owners wanting auxiliary fuel and a toolbox in one combination should consider this 60-gallon RDS unit. Check the 55-by-20-by-19.5-inch dimensions against the bed, especially if other cargo or equipment needs that space.

Listed on Amazon as: RDS MFG INC – 72548 Fuel Transfer Tank/Auxiliary Fuel Tank/Toolbox Combo – 60 Gallon

#6

6. Dee Zee DZ92740XB Combo

• Weight: 50 lb

Best for: Diesel tank with utility chest.

Why it ranks #6: This 43-gallon auxiliary diesel transfer tank combines a toolbox with .125-inch Brite-Tread aluminum, three stability baffles, and a lockable cap.

A bolted-on utility chest paired with a 43-gallon tank gives this Dee Zee unit a two-purpose truck-bed setup for auxiliary diesel and storage. Its Brite-Tread aluminum construction and black powder-coat finish distinguish the material and surface treatment, while the listing identifies it specifically as an auxiliary diesel transfer tank.

The combination of a transfer tank and bolted-on storage chest lets owners carry fuel and equipment in one assembly. Dee Zee specifies .125-inch Brite-Tread aluminum and a black powder-coat finish, providing concrete construction details. Three stability baffles, a lockable cap, a 3/8-inch drain plug, and a venting coupler support evaluation of liquid handling and maintenance. The listed 43-gallon capacity and 54-inch overall length help assess reserve size and truck-bed placement.

Skip it if you need a 92-gallon steel tank with storage; Dee Zee DZ92647SB offers that larger capacity and a toolbox combination.

This fits truck owners wanting a named auxiliary diesel tank with a utility chest, aluminum construction, and listed baffles. Its 43-gallon capacity and 54-inch length remain key boundaries when matching fuel needs and bed space.

Listed on Amazon as: Dee Zee DZ92740XB (43 gallon) Auxiliary Diesel Fuel Transfer Tank – Black Aluminum

#7

7. Landrol 58-Gallon Tank

• Capacity: 58 gallons
• Material: Aluminum
• Compatible with Vehicle Type: Transportation Truck

Best for: Removable aluminum truck tank.

Why it ranks #7: Its 58-gallon aluminum tank lists a fuel gauge sending unit, oil pipes, vent covers, and mounting brackets, but explicitly says it is not DOT certified.

Two straps and fully welded mounting brackets make this 58-gallon Landrol tank notable for owners who want a truck-mounted tank that can also be removed. Its aluminum construction and listed 59-by-13-by-17-inch size add useful weight and fit considerations for transporting and storing non-flammable liquids.

Landrol describes fully welded mounting brackets for attaching the tank to a truck and two straps for quick removal, giving the setup a removable-use workflow rather than a permanently fixed arrangement. The 58-gallon capacity and 59-by-13-by-17-inch dimensions help assess storage and bed placement. Oil pipes, vent covers, and a sending unit connected to a fuel gauge support checking remaining capacity. The manufacturer explicitly says the tank has not been DOT certified.

Skip it if you require stated DOT certification; RDS MFG INC 71083 describes diesel gravity-feed capability, though its supplied details do not state certification.

This suits truck owners transporting non-flammable liquids who value a removable tank, gauge sending unit, and substantial capacity. The lack of DOT certification is a clear boundary, and the 59-inch length merits a bed-fit check.

Listed on Amazon as: 58 Gallon Aluminum Fuel Cell Tank Rectangular Transfer Fuel Tank Auxiliary Diesel Storage for Transportation Truck

#8

8. Dee Zee DZ92647SB Combo

• Capacity: 92 gallons
• Material: Alloy Steel
• Weight: 49 lb

Best for: High-capacity toolbox combination.

Why it ranks #8: The 92-gallon steel combo offers a bolted-on storage compartment and NRT powder coat, but the listing does not specify diesel auxiliary-feed operation.

A 92-gallon tank combined with bolted-on storage makes this Dee Zee a high-capacity option for truck owners who also carry tools and equipment. Its 14-gauge steel construction and NRT powder-coat finish provide concrete durability and corrosion-protection details for buyers comparing bed-mounted fuel-and-storage combinations.

The 92-gallon capacity gives this combo a substantial transfer-tank volume, while the bolted-on compartment offers a separate place for tools and equipment. Dee Zee specifies 14-gauge steel and an NRT powder-coat finish intended to increase corrosion protection. The additional description identifies a radius-curve design, stability baffle, lockable cap, drain plug, and venting, useful details for evaluating handling and upkeep; the supplied dimensions are 32.75 inches wide by 25.38 inches high.

Skip it if you prefer aluminum construction over steel; Dee Zee DZ92740XB is a 43-gallon Brite-Tread aluminum auxiliary diesel tank.

Truck owners needing substantial transfer capacity alongside tool storage may value this Dee Zee combo. Its steel construction and 25.38-inch listed height are important considerations, particularly where cover clearance or material preference constrains the setup.

Listed on Amazon as: Dee Zee DZ92647SB (92 gallon) Black Steel Combo Transfer Tank & Tool Box

#9

9. Dee Zee DZ92556NSB Tank

• Capacity: 128 liters
• Material: Alloy Steel
• Weight: 70 lb

Best for: Baffled steel-bed transport.

Why it ranks #9: This 42-gallon steel transfer tank has five stability baffles, mounting tabs, and a three-year limited warranty, but no listed auxiliary diesel-feed method.

Five stability baffles distinguish this Dee Zee 42-gallon steel transfer tank, helping address fluid movement during transport. Its 14-gauge steel body, mounting tabs, and drain plug give truck owners practical construction and securing details to weigh when planning a bed-mounted tank for non-flammable liquids.

The 14-gauge steel construction and radius-curve design are intended to reduce pressure at weld points, while five stability baffles support steadier liquid transport. Mounting tabs provide a means to secure the tank to the truck bed, and the drain plug supports draining when needed. The 59.5-inch width and 19-inch height help establish fit, but the supplied description identifies non-flammable liquids rather than specifically establishing a diesel connection to the vehicle tank.

Skip it if you need a stated gravity-feed connection to the vehicle tank; RDS MFG INC 71083 explicitly describes diesel gravity-feed capability.

This is a candidate for truck owners transporting non-flammable liquid who value baffles, steel construction, and bed mounting tabs. Buyers seeking a documented diesel connection to the vehicle fuel system should treat that as an unresolved fit.

Listed on Amazon as: Dee Zee DZ92556NSB Transfer Tank

#10

10. dreamdragon 45-Gallon Tank

• Capacity: 45 gallons
• Material: Aluminum
• Compatible with Vehicle Type: Truck

Best for: Upright hydraulic reservoir storage.

Why it ranks #10: Despite its 45-gallon aluminum capacity, the description identifies it as a hydraulic oil reservoir, so it is the least suitable match for diesel auxiliary use.

Its upright 45-gallon reservoir format is the defining feature, offering substantial fluid storage in an aluminum tank for equipment owners considering a hydraulic system. The listing also calls out heat dissipation and corrosion resistance, but identifies the contents as hydraulic oil, so diesel buyers should distinguish its stated application from a fuel tank.

The 45-gallon capacity and upright rectangular form provide substantial reservoir volume, while aluminum construction is described as lightweight, corrosion-resistant, and heat-efficient. Those traits may matter in equipment applications where weight and heat dissipation are concerns. The listing mentions a complete installation kit and warns not to fill beyond the indicated level because overfilling may cause leakage. Since its details specify hydraulic oil, they do not establish diesel-fuel compatibility or auxiliary fuel-system operation.

Skip it if you need a clearly specified diesel auxiliary tank; Dee Zee DZ92740XB is explicitly titled as an auxiliary diesel transfer tank.

This fits buyers seeking a 45-gallon upright hydraulic reservoir with aluminum construction and an installation kit. It is not a straightforward diesel-roundup choice: the supplied description specifies hydraulic oil, and overfilling is cautioned against.

Listed on Amazon as: 45 Gallon Rectangular Auxiliary Fuel Tank