Key Takeaways:
- The Factory Setup Has A Gap: The single-stick Dana 20 does not allow independent front and rear axle engagement, limiting trail control significantly.
- Twin Stick Fills That Gap: The Twin Stick Shifter for the 66–77 Bronco opens transfer case control options the factory configuration cannot provide.
- High Value Upgrade: The Twin Stick Shifter is one of the highest capability-per-dollar upgrades available for the early Bronco Dana 20.
Most early Bronco owners do not know their transfer case has a control gap until they drive a twin stick conversion. After that, going back to the factory single-stick setup feels like a step backward that is hard to justify.
TOMS OFFROAD carries the 66–77 Ford Bronco Dana 20 Twin Stick Shifter, a direct upgrade that opens transfer case control options the factory configuration was never designed to provide.
This page covers what the factory setup lacks, what changes with the twin stick conversion, how the Dana 20 works, and how to install it correctly.
The Control Gap In The Factory Dana 20 Setup
The factory Dana 20 single-stick setup works. What it does not do is give the driver independent control over front and rear axle engagement on the trail.
How The Factory Single-stick Setup Works
The factory Dana 20 on the 66–77 Bronco uses a single shifter that controls both the range selection and the front axle engagement together. The driver selects 2-High, 4-High, or 4-Low as combined positions. There is no factory provision for running the transfer case in low range without simultaneously engaging the front axle throughout the operation.
What Is A Twin Stick Transfer Case: What Independent Control Means
A twin stick conversion splits the transfer case shifting function into two independent levers. One lever controls range selection between high and low. The other controls front axle engagement independently. This separation gives the driver control combinations the single-stick setup cannot achieve, regardless of how the factory shifter is positioned on the trail.
Where The Single-stick Limitation Shows Up
The limitation becomes apparent on technical trail sections where rear-wheel drive in low range is the correct approach. The factory setup forces front axle engagement whenever low range is selected. The twin stick conversion removes that constraint and gives the driver the correct tool for each specific trail situation encountered.
Why Most Early Bronco Owners Do Not Know The Gap Exists
Owners who have only driven a single-stick early Bronco have no reference point for what independent control feels like. The factory setup handles most trail situations adequately enough that the gap is never obvious until a twin stick conversion reveals what was missing throughout every previous trail run.
Planning upgrades like this before the build begins rather than discovering them mid-project is exactly what our guide on basic tips for planning your classic Ford Bronco restoration addresses.
What Changes With A Twin Stick Conversion
The 66–77 Ford Bronco Dana 20 Twin Stick Shifter from TOMS OFFROAD opens transfer case control options that the factory configuration simply does not offer.
- Independent Front Engagement: Front axle engagement and range selection operate independently, giving the driver precise control over which axles are driven at any point on the trail.
- Early Bronco Twin Stick Conversion: Low Range Without Front Drive: The driver can select low range with rear-wheel drive only, a combination the factory single-stick setup cannot achieve under any shifting position.
- Rear-Wheel Drive In Low Range: Running rear-only in low range allows controlled momentum on loose surfaces where front axle engagement would break traction and reduce control.
- Trail Precision Across All Conditions: The full range of transfer case combinations available with the twin stick gives the driver the right setup for every trail condition rather than a compromise position.
Understanding The Dana 20 Transfer Case
Before the twin stick conversion makes full sense, understanding what the Dana 20 is and how it works clarifies exactly what the conversion changes.
What The Dana 20 Is And Which Early Broncos Used It
The Dana 20 is a part-time four-wheel-drive transfer case used in the 1966–77 Ford Bronco. It is a gear driven unit with a two-speed range capability and a front axle engagement provision built into the single factory shifter assembly. It is a robust and well-regarded unit that forms a strong foundation for the twin stick conversion.
Twin Stick Transfer Case Bronco: How The Dana 20 Works Internally
The Dana 20 uses dual shifts rail internally that controls both range and front axle engagement through the factory shifter linkage. The twin stick conversion replaces the external shifter assembly and linkage with a two-lever system that operates the internal shift functions independently.
Why The Dana 20 Is A Strong Foundation
The Dana 20's internal construction is robust enough to handle the demands of trail use that the twin stick conversion enables. The case itself does not require modification for the shifter installation, which keeps the conversion straightforward and reversible if the builder's requirements change over time.
Installing The Twin Stick Shifter On A 66-77 Bronco
Installation of the Dana 20 Twin Stick Shifter on a 66–77 Bronco follows a straightforward process when the correct sequence is used from the start.
- Transfer Case Access And Prep: Gain clean access to the transfer case shifter area and document the factory linkage configuration before removing any components from the assembly.
- Factory Shifter Removal: Remove the factory single-stick shifter and linkage completely, retaining all hardware for reference during the twin stick installation and alignment process.
- Installation And Alignment: Install the twin stick assembly, connect the linkage to both transfer case shift functions, and verify smooth independent operation of both levers before closing up.
- Function Test Before Trail Use: Test all transfer case combinations, including rear-only low range on a flat surface before the first trail run to confirm correct independent operation throughout.
A correctly installed twin stick conversion gives the early Bronco driver transfer case control that the factory single-stick setup was never designed to provide. For enthusiasts managing a broader Classic Bronco build alongside the drivetrain upgrade, our guide on Bronco restoration covers the full scope of what the platform needs.
Final Thoughts
The twin stick transfer case bronco upgrade is one of those modifications that owners wish they had done earlier, once they experience what independent front and rear control actually feels like on the trail.
TOMS OFFROAD has supported early Bronco drivetrain builds since 1976 and carries the Twin Stick Shifter built specifically for the 66–77 Dana 20 application at $189.95. For enthusiasts managing the full scope of a Classic Bronco build beyond the drivetrain, the early Bronco restoration hub covers every system the 1966–77 platform needs addressed correctly.
Browse all Ford Bronco parts from TOMS OFFROAD to support every other stage of the build.
One upgrade. Permanent improvement. The catalog is here.
Frequently Asked Questions About Twin Stick Transfer Case Bronco
What is a twin stick transfer case on an early Bronco?
It is a two-lever shifter conversion that allows independent control of range selection and front axle engagement separately.
What transfer case does the 66–77 Ford Bronco use?
The 1966–77 Ford Bronco uses the Dana 20 part-time four-wheel-drive transfer case as standard equipment.
What does the TOMS OFFROAD Twin Stick Shifter cost?
The 66–77 Ford Bronco Dana 20 Twin Stick Shifter is available through TOMS OFFROAD starting at $189.95.
Does the twin stick conversion require internal Dana 20 modification?
Yes and no. You can install the twin sticks without removing the shift rails and detents but will not be a true twin stick. To be a true twin stick application you will need to replace the shift rails with our Toms Offroad Twin Stick Shift Rails. These rails are not compatible with the factory single-handle shifter. When installed according to the supplied instructions, the shift rails eliminate the possibility of cross-shifting (incorrect high/low combinations), ensuring safe and reliable transfer case operation. This will also require a full rebuild of the Dana 20.
Is the twin stick conversion reversible on a Classic Bronco?
Yes, the external nature of the conversion means it can be reversed without permanent modification to the Dana 20 transfer case.
