THE STRONGBOX UNDERDRIVE SERIES

Powerful Underdrives for Dana 300s, NP205s, Rangers and more.

To find the right model for your build, please enter the your transmission output, and transfer case input below to see the Strongbox models that fit your vehicle:

RANGER STANDARD MODEL

Our ready to install, fully geared D300 Colossus comes with 4:1 LowMax Gears from JB Conversions

LEARN MORE - CLICK HERE

NV241 STANDARD STRONGBOX

The DIY NP205 Colossus Case is compatible with both Stock NP205 Gears, or the 3:1 LowMax Gearset. Choose what's best for your build.

LEAN MORE - CLICK HERE

NV271 STANDARD STRONGBOX

Our ready to install, fully geared NP205 Colossus is available in both Stock Gear and 3:1 LowMax Gears from JB Conversions

LEARN MORE - CLICK HERE

NP205 *SHORTY* STRONGBOX

The DIY NP205 Colossus Case is compatible with both Stock NP205 Gears, or the 3:1 LowMax Gearset. Choose what's best for your build.

LEAN MORE - CLICK HERE

DANA 300 *SHORTY*STRONGOX

The DIY NP205 Colossus Case is compatible with both Stock NP205 Gears, or the 3:1 LowMax Gearset. Choose what's best for your build.

LEAN MORE - CLICK HERE

AGGRESSIVE PERFORMANCE IN THE REAL WORLD

Don't ask us - here's what the customers are saying:

Drivetrain Length Specs by Model

Standard NP241 32 Spline Strongbox - Adds 8 Inches to Drivetrain Length

.

Standard NP241 31 Spline Strongbox - Adds 8 Inches to Drivetrain Length

.

Standard NP241 23 Spline Strongbox (S) - Adds 8 Inches to Drivetrain Length

.

Standard NP241 23 Spline Strongbox (L) - Adds 8 Inches to Drivetrain Length

.

NP241 Dana 300 SHORTY Strongbox - Adds 5.5 Inches to Drivetrain Length

.

NV241 Strongbox for NP205 90mm Spline - Adds 5.5 Inches to Drivetrain Length

.

NV241 Strongbox for NP205 80mm Spline - Adds 5.5 Inches to Drivetrain Length

.

Ranger Standard Strongbox - Adds 7 Inches to Drivetrain Length

.

Ranger SHORTY Strongbox - Adds 4.4 Inches to Drivetrain Length

.

Standard NV271 32 Spline Strongbox - Adds 8 Inches to Drivetrain Length

.

Standard NV271 31 Spline Strongbox - Adds 8 Inches to Drivetrain Length

.

Standard NV271 23 Spline Strongbox (S) - Adds 8 Inches to Drivetrain Length

.

Standard NV271 23 Spline Strongbox (L) - Adds 8 Inches to Drivetrain Length

.

NV271 Dana 300 SHORTY Strongbox - Adds 5.5 Inches to Drivetrain Length

.

NP271 Strongbox for NP205 90mm Spline - Adds 5.5 Inches to Drivetrain Length

.

NP271 Strongbox for NP205 80mm Spline - Adds 5.5 Inches to Drivetrain Length

Have Technical or Compatibility Questions?

Have questions about compatibility or specific technical questions for your build?

Give our team a call at (855) 928-1984 and one of our staff engineers will gladly help step you through aspect of compatibility, and the build process you need.

WANT WHOLESALE PRICING?

Are you a vehicle builder or design/fab shop? We have a wholesale program just for builders! Click HERE to get more info on our wholesale program and receive discounts off retail, additional engineering support, custom options, cash back and more.