Early Bronco Stock Fuel Tanks

Early Bronco Stock Gas Tank Specifications (1966-77 Ford Bronco)

From the factory, the 1966-77 Ford Bronco came with a simple, practical fuel tank setup that reflected its rugged 4x4 roots. These classic Broncos were equipped with either a single rear fuel tank or a dual tank configuration that included a front auxiliary tank. Understanding the stock setup is important when restoring, upgrading, or troubleshooting your Early Bronco fuel system.

Rear Main Fuel Tank – 1966-77 Ford Bronco

Every 66-77 Ford Bronco came standard with a rear main fuel tank mounted between the frame rails, just forward of the rear bumper.

The 1977 Bronco received a redesigned rear tank. While the capacity increased slightly and materials changed, the mounting location remained the same.

Rear Tank Specifications (1966-76 Ford Bronco)

• Location: Between frame rails, ahead of rear bumper

• Capacity: Approximately 13 gallons

• Material: Galvanized steel

• Mounting: Single strap with J-bolt

• Protection: Steel skid plate

The 1966-76 rear fuel tank was constructed from galvanized steel for corrosion resistance. It was secured using a steel skid plate sandwiched to the tank by a single mounting strap and J-bolt.

With only 13 gallons of fuel capacity, driving range was modest—especially for trail rigs or Broncos running larger tires and lower gearing.

Rear Tank Specifications (1977 Ford Bronco)

• Location: Between frame rails, ahead of rear bumper

• Capacity: Approximately 14 gallons

• Material: Plastic

• Mounting: Steel skid plate mount system

• Protection: Steel skid plate

For 1977, Ford switched to a plastic rear fuel tank mounted within a steel skid plate that covered the full underside of the tank rather than just the rear of the tank like the 66-76 Bronco skid plate. Capacity increased slightly to approximately 14 gallons, but overall placement remained unchanged.

Front Auxiliary Fuel Tank – 1966-77 Ford Bronco

Many Early Broncos were ordered with the optional front auxiliary fuel tank located under the driver-side seat. This secondary tank significantly increased fuel range and became a popular factory option.

Front Auxiliary Tank Specifications

• Location: Under driver-side seat

• Capacity: 8 gallons

• Material: Plastic

• Mounting: Dual straps with J-bolts

• Protection: Factory skid plate included

Unlike the early steel rear tank, the auxiliary tank was plastic. It always came equipped with a full length skid plate. The skid plate protected the tank from rocks and road hazards while also preventing the mounting straps from wearing into the plastic over time. Although minor variations occurred through the years, the auxiliary tank design remained largely consistent throughout 1966-77 production.

Total Early Bronco Fuel Capacity (Dual Tank Setup)

When equipped with both tanks, total fuel capacity was as follows:

1966-76 Ford Bronco

• Rear Main Fuel Tank: 13 gallons

• Front Auxiliary Fuel Tank: 8 gallons

• Total Capacity: 21 gallons

1977 Ford Bronco

• Rear Main Fuel Tank: 14 gallons

• Front Auxiliary Fuel Tank: 8 gallons

• Total Capacity: 22 gallons

Adding the auxiliary tank increased total fuel capacity by over 60% compared to a rear tank alone. Considering the fuel demands of carbureted V8 engines and early 4x4 drivetrains, the dual tank setup offered a significant improvement in driving range.

Why Most Early Broncos Came with Dual Fuel Tanks

Because the standard rear tank held just 13 gallons (14 gallons in 1977), most buyers opted for the dual fuel tank configuration. The additional 8-gallon auxiliary tank made a noticeable difference in range—especially for off-road use, rural driving, or long highway trips.

For restoration projects or fuel system upgrades, knowing whether your 1966-77 Ford Bronco originally had a single or dual tank setup will help guide tank selection, skid plate choices, and proper fuel line routing.

If you're rebuilding your Early Bronco fuel system, upgrading tank capacity, or replacing worn components, understanding these factory gas tank specifications is the first step toward keeping your classic Bronco on the road and on the trail.