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Gear Vendors Under / Overdrive Systems

Auxiliary Overdrive Systems for GM, Ford, and Dodge – Now Available at Cruisin Automotive

Cruisin Automotive is proud to supply and install Gear Vendors Overdrive units for street and performance builds across Australia. Designed to multiply torque, expand gear ratios, and handle huge horsepower, Gear Vendors are the gold standard for auxiliary overdrive transmission performance.

What’s Available – Gear Vendors Applications

Gear Vendors overdrive units are compatible with a wide range of GM, Ford, and Dodge transmissions, offering up to twice the number of forward gear ratios and improving drivability across both street and race applications.

We supply and install units for:

  • GM Powerglide 2-Speed
    • Part #3DG100A: 11″ Tailhousing
    • Part #3DG101A: Shorty Version

  • GM ST-300 2-Speed
    • Part #3DFS300A

  • GM 3-Speed Transmissions
    • Part #3DFS353A: Shorty
    • Part #3DFS354A: Xtra-short

  • TH400 3-Speed (Electrical Speedo)
    • Part #3DFS401A: 4″ Tailhousing

 

Use this chart to calculate your real-world gearing gains based on your transmission and differential setup.

The Final Drive Ratio shows you how many times the engine turns for one complete turn of the tires. Gears are multiplier of torque.

The Final Drive Ratio determines how many engine revolutions occur for every complete wheel rotation. Adding Gear Vendors enhances torque multiplication and optimises highway cruising RPM.

TH350 3-SPEED AUTOMATIC
Trans Ratio 4.56 4.10 3.73 3.55 3.42 3.08
1st (2.52) 11.49 10.33 9.40 8.95 8.62 7.76
Over (1.97) 8.96 8.06 7.33 6.98 6.72 6.05
2nd (1.52) 6.93 6.23 5.67 5.40 5.20 4.68
Over (1.19) 5.41 4.86 4.42 4.20 4.06 3.65
3rd (1.00) 4.56 4.10 3.73 3.55 3.42 3.08
Over (0.78) 3.56 3.20 2.91 2.77 2.67 2.40

How It Works

Step 1: Select Your Transmission Type

Let us know what transmission you’re running—GM, Ford, or Dodge—and we’ll match the right Gear Vendors part number to your setup.

Step 2: Understand the Gains

We’ll help you calculate your new final drive ratio using our chart and show you where you’ll benefit across the rev range.

Step 3: Installation or Shipping

Have your system fitted professionally at our Malaga workshop or shipped anywhere in Australia for DIY or workshop install.

Step 4: Setup and Test

We ensure proper driveline alignment, electronic control integration, and on-road testing for in-house installs.

Part # 3DG100A | Automatic 2-Speed Power Glide 11″ Tailhousing

Part # 3DG101A | Automatic 2-Speed Power Glide Shorty

Part # 3DFS300A | Automatic 2-Speed ST-300

Part # 3DFS353A | Automatic 3-Speed Shorty

Part # 3DFS354A | Automatic 3-Speed xtra-short

Part # 3DFS401A | Automatic 3-Speed TH 400 – 4″ Tailhousing – Electrical Speedo

Why Choose Gear Vendors?

  • True Overdrive Performance
    Up to 0.78:1 gear reduction means lower cruise RPM and better economy without sacrificing torque.
  • Race Proven Strength
    Handles up to 1200+ horsepower—perfect for high-output street machines, hot rods, and drag applications.
  • Simple Integration
    Fits between your transmission and tailshaft with minimal modifications required.
  • Dual Range Driving
    Split gears on-the-fly for up to 6 forward ratios from a 3-speed automatic.
  • Unmatched Durability
    Built with precision and strength in mind—this is the last overdrive your drivetrain will ever need.
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Frequently Asked Questions

What transmissions are Gear Vendors compatible with?

We supply units for GM (Powerglide, ST-300, TH350, TH400), Ford C4/C6/AOD, and Dodge Torqueflite setups.

Yes—Gear Vendors units often outperform modern boxes in torque handling, gear range flexibility, and simplicity.

Usually yes. We provide advice or services to shorten tailshafts and adjust mounts accordingly.

Absolutely. Book your install at our Malaga facility and we’ll set it up ready to drive.

Yes. We supply and ship Gear Vendors products to every state and territory in Australia.

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