Doublerô Quick Facts and FAQ answers

Gear reduction of NP203 gearbox: 2.01:1
Gear reduction of NP205: 1.96:1
Gear Ratio of combined transfer cases: 3.94 (basically 4:1)
Overall Length of assembled 203 with NP205: 21.5" from front of 203 to ujoint center
Overall weight of Doublerô assembled with 203 and 205: approximately 240#
Weight of Doublerô kit: 24#

The lowest point on the NP203 is about 8.5" below the drivetrain centerline. The NP205 is easily rotated to match.

The NP203 transfer case was used in GM, Ford and Dodge trucks behind these transmissions:
TH350, TH400, SM465
NP435, TF727
C6, NP435

The NP203 gearbox is adaptable to many other transmissions but can use a factory adapter with the above mentioned transmissions.

If you have a Ford front axle (or other application with the differential on the driver side) you need to use a Ford NP205. If you have a GM front axle (or other application with the differential on the passenger side), you need to use a GM NP205. The 203 and 205 do not need to be the same brand, we can mix and match to suit the parts you want to use.

The GM or Dodge Doublerô kit requires a 32 spline input NP205 which came in GM trucks with a TH400 transmission. Your first choice is a TH400 version from '84 and older.  This will have a short 32 spline input and a figure 8 bolt pattern.  2nd choice is a 205 from '85-up that will require a short 32 spline input swap since the input is too long.  We also have a conversion kit to turn other versions of the NP205 into a 32 spline input with a little more work involved.

Ford applications will use any married ford NP205. All Ford married 205's came with a 31 spline female input gear. No modifications to this case are required.

We recommend dual crossmembers for mounting the Doubler system. You can use lightly modified factory crossmembers for many applications or click here for some ideas on custom high clearance mounting.